How to allow premium users to build, upload, rate, and download user-created levels?

I have an Android 2d platformer with a level builder, I want premium users to be able to build levels and upload them to a server where they can browse, download, and rate levels built by others.

So would this be done by...

For a player to upload a level they made:

Generate an asset bundle in real time

Take a screenshot to use as thumbnail

Store the assetbundle and screenshot on a cloud storage service

For a player to download and play a level

In the level browser scene display the screenshot and

Player can click the screenshot to then downloads the asset bundle from the cloud server,

Loads a new scene with said asset bundle? Or can the assetbundle be a whole scene?

Do you know any good cloud storage services that can do this and also as a bonus manage the login and payment, and also some analytics with a good web based dashboard to visualise the data would be great (I know, I'm asking for a lot).

I've no experience with real time generated content at all so any and all advice welcome

This is a repost as my original post was never approved/disapproved by the moderators,it seemed to just get stuck in the queue for 2 days