Unity problem when i convert playerprefs save to the standard file io save

i am using tow kind of save the main save which is encrypting save that is using in this video (https://www.youtube.com/watch?v=XOjd_qU2Ido&t=351s) and playerprefs save when i use them together with the playerprefs only works when i disable the playerprefs the encrypting save work how to make them work together
the playerprefs comes as cs script when i bought daily reward from the asset store this the cs script that contain the playerprefs so i got a problem when i convert playerprefs save to the standard file io save any help

 using UnityEngine;
 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Globalization;
 
 namespace NiobiumStudios
 {
     /**
     * Timed Rewards Canvas is the User interface to show Timed rewards
     **/
     public class TimedRewards : DailyRewardsCore<TimedRewards>
     {
         public DateTime lastRewardTime;     // The last time the user clicked in a reward
         public TimeSpan timer;
         public float maxTime = 3600f; // How many seconds until the player can claim the reward
         public bool isRewardRandom = false;     // Is the reward random or the player chooses from available rewards?
 
         public List<Reward> rewards;
 
         public delegate void OnCanClaim();              // When the player can claim the reward
         public OnCanClaim onCanClaim;
 
         public delegate void OnClaimPrize(int index);   // When the player claims the prize
         public OnClaimPrize onClaimPrize;
 
         private bool canClaim;              // Checks if the user can claim the reward
 
         // Needed Constants
         private const string TIMED_REWARDS_TIME = "TimedRewardsTime";
         private const string FMT = "O";
         
         void Start()
         {
             StartCoroutine(InitializeTimer());
         }
 
         // Initializes the timer in case the user already have a player preference
         private IEnumerator InitializeTimer()
         {
             yield return StartCoroutine(base.InitializeDate());
 
             if (base.isErrorConnect)
             {
                 if(onInitialize!=null)
                     onInitialize(true, base.errorMessage);
             }
             else
             {
                 LoadTimerData();
 
                 if(onInitialize!=null)
                     onInitialize();
 
                 CheckCanClaim();
             }
         }
 
         void LoadTimerData ()
         {
             string lastRewardTimeStr = PlayerPrefs.GetString(GetTimedRewardsTimeKey());
 
             if (!string.IsNullOrEmpty(lastRewardTimeStr))
             {
                 lastRewardTime = DateTime.ParseExact(lastRewardTimeStr, FMT, CultureInfo.InvariantCulture);
                 timer = (lastRewardTime - now).Add(TimeSpan.FromSeconds(maxTime));
             }
             else
             {
                 timer = TimeSpan.FromSeconds(maxTime);
             }
         }
 
         protected override void OnApplicationPause(bool pauseStatus)
         {
             base.OnApplicationPause(pauseStatus);
             LoadTimerData();
             CheckCanClaim();
         }
 
         public override void TickTime()
         {
             base.TickTime();
             if(isInitialized)
             {
                 // Keeps ticking until the player claims
                 if (!canClaim)
                 {
                     timer = timer.Subtract(TimeSpan.FromSeconds(Time.unscaledDeltaTime));
                     CheckCanClaim();
                 }
             }
         }
 
         public void CheckCanClaim ()
         {
             if (timer.TotalSeconds <= 0)
             {
                 canClaim = true;
                 if (onCanClaim != null)
                     onCanClaim();
             }
             else
             {
                 // We need to save the player time every tick. If the player exits the game the information keeps logged
                 // For perfomance issues you can save this information when the player switches scenes or quits the application
                 PlayerPrefs.SetString(GetTimedRewardsTimeKey(), now.Add(timer - TimeSpan.FromSeconds(maxTime)).ToString(FMT));
             }
         }
 
         //Returns the TimeRewardsTime playerPrefs key depending on instanceId
         private string GetTimedRewardsTimeKey()
         {
             if (instanceId == 0)
                 return TIMED_REWARDS_TIME;
 
             return string.Format("{0}_{1}", TIMED_REWARDS_TIME, instanceId);
         }
 
         // The player claimed the prize. We need to reset to restart the timer
         public void ClaimReward(int rewardIdx)
         {
             PlayerPrefs.SetString(GetTimedRewardsTimeKey(), now.Add(timer - TimeSpan.FromSeconds(maxTime)).ToString(FMT));
             timer = TimeSpan.FromSeconds(maxTime);
 
             canClaim = false;
 
             if (onClaimPrize != null)
                 onClaimPrize(rewardIdx);
         }
 
         public string GetFormattedTime()
         {
             if(timer.Days > 0) 
                 return string.Format("{0:D2} days {1:D2}:{2:D2}:{0:D3}", timer.Days, timer.Hours, timer.Minutes, timer.Seconds);
             else
                 return string.Format("{0:D2}:{1:D2}:{2:D2}", timer.Hours, timer.Minutes, timer.Seconds);
         }
 
         // Resets the Timed Rewards. For debug purposes
         public void Reset()
         {
             PlayerPrefs.DeleteKey(GetTimedRewardsTimeKey());
             canClaim = true;
             timer = TimeSpan.FromSeconds(0);
 
             if (onCanClaim != null)
                 onCanClaim();
         }
 
         // Returns a reward from an index
         public Reward GetReward(int index)
         {
             return rewards[index];
         }
     }
 }