@pfeifakopf I did solve it.
I had to create the MySQL user and assign all database permissions manually. This can be done in command line or by installing PHPMyAdmin.
In the dashbaord of these modern hosting platforms, you can see the user being created. But they do not GRANT permissions or allow you to manage db permissions from the UI. This is by design and I have confirmed with their support teams. See the following note from Cleavr support. I think it would be nice if they made that clear. But in my testing of all of them, I never saw that information published anywhere.
Ah! Yeah, we don’t allow for changing permissions to db users via the dashboard, generally. As we don’t like the potential security risks. You’d need to update permissions via SSH terminal.