Re: SharePoint integration with powerapps portal
Hi @anjanyad
FYI. Some of the key points to solve this error. Please start fresh.

Probably the below steps will hopefully fix your errors
Pre: In Power Apps portal Admin center > Document Management Settings > Choose Online> Provide your site complete setup

2. Then follow the Microsoft docs (Step 2 and Step 3)
3. For Step 4: Create and Use the different basic forms to create and edit the records
4. Add subgrid only for Edit or view forms ( Not for create)
5. Step 5 from Microsoft doc is the key. Table permission for the "Document Location" entity is a must.
once done.
In portal studio > sync config > Browse the website > Ctrl + F5 (Hard refresh) to see your SharePoint integration
Hope it helps.
------------
If you like this post, give it a Thumbs up. Where it solved your request, Mark it as a Solution to enable other users to find it.