How to Clamp A RigidBody to the Ground/ Moving a RigidBody Along the Ground

Hello! this is my very first Question here!/sorry for my english.

Currently I am writing a RigidBody Character Controller, and I'm having some trouble.

if I move the RB on a flat surface everything is fine, but as soon as there is a slope (like 20°),

it starts to go forward, then its in the air and falls to the ground, then it detects the Ground and falls again, it moves like on stairs, but its a steady slope.

Now I want that the RB moves along the Ground, but stays upright. I already have a version of that working, but the Capsules Y Axis just alligns with the Normal.

I'm adding the Code snippet that allows me to do that. ( its not just Capsule.up = Ground.normal)

 void FixedUpdate () 
     {
         // ControllerInput
         float DirH = Input.GetAxis("LSX");
         float DirV = Input.GetAxis("LSY");
 
          DetectGround();  //SphereCast Down, Mathf.Infinity, measures distance.
 
          if (onGround == true)
         {
             if (DirH != 0 || DirV != 0)
             {
                 flippedCharCamera = (CharCamera.forward * -1);     //CharCamera is the Main Camera
                 CharDirection = DirV * flippedCharCamera + DirH * CharCamera.right;                // Calculation of the Movement
                 expectedPlayerPosition = CharRb.transform.position + CharDirection * charSpeed * Time.deltaTime;    // Expected Player Position, CharRb is the RigidBody Character Controller
 
  Physics.Raycast(Player.position, CharDirection - (Player.up + new Vector3(0, 2f, 0)), out AddGroundInfo, Mathf.Infinity, CharMask);    //CharMask ignores the Layer the Controller is in
 
 Vector3 MagentaDirection = (groundSphereInfo.point - AddGroundInfo.point) * -1;   //groundSphereInfo is the RaycastHIt of the SphereCast in DetectGround();
                     CharDirection = Vector3.Project(CharDirection, MagentaDirection);
                     CharRb.MovePosition(CharRb.transform.position + CharDirection * charSpeed * Time.deltaTime);   //charSpeed is a float 12f;
 
 }
 }
 }
 
 
 

I am stuck at this... please send help!