In this post we can explore how to configure App User Permissions.
App User should not be System Account. If you have not created an App User, you can follow the post below to create one.
Farm Administrator Permission
Login as Administrator to the machine. Open Central Administration > Farm Administrators.
Add App User to the group.
Site Collection Administrator Permission
Login as Administrator to the SharePoint site. Open Site Settings > Site Permissions.
Add the App User to the group.
Click Ok to save changes.
Database Owner Permission
Login as Administrator to the machine. Open SQL Server Management Studio. Create a new Login for App User.
Once the user is created, open the user properties > User Mapping section and assign db_owner permission on all SharePoint databases. You need to select each database and check the db_owner property. Once you checked for all the databases Click the Ok button to save changes.
In this post we have explored how to configure App User Permissions.