Exchange Mailbox AutoProvisioning Error

Hey all,

Im getting the following error when users try to create a user with a mailbox. "Provisioning policy failure. The 'Exchange Mailbox AutoProvisioning' policy encountered an error. Invalid Administrative Policy settings.".. It works fine for us with admin rights inside ARS but for those who dont it doesnt work. 

We have had a major change which im quite sure is related and that is we have upgraded exchange to 2019 (built new servers). The old servers are still around and are still accepting mail for now but all databases have been migrated to 19, since the migration is when we started experiencing the issue. 

All permissions have carried forward (to my knowledge) from 13 to 19, and i've even gone as far as adding the quest service and the user into Exchange admins to test with no joy. 

I've gong into each of our Exchange DB policies and selected the databases per OU and the databases show up inside the policy.

Where else do i need to set exchange settings/servers or what permissions could i be missing here?

Thank you for your help