It has been a while since I created a new database. And perhaps I have always created them on Mac in the past. I recently created a new database in DTTG and I cannot remember how to open it in DT. And I can’t find the answer in the documents.
As we’ve often discussed, every device has its own copy of the databases but can sync to a commonly accessible location. So you need to import the database into DEVONthink via a supported Sync method. What are you using now?
If you’re syncing the new database via a CloudKit sync, you’d import it from the CloudKit sync location in DEVONthink on your Mac.
PS: As we’ve also often discussed, sync is optional. Just creating a database doesn’t make it automatically start syncing. That’s definitely by design and a decision the user, not the software, must make.