On the side bar under Open Databases is a list of the databases that are open.
When I sync, I sync the entire database. In the screenshot for my Active database, what is the Sync group for and when would I use it/it be used?
Did you create this database using older version of DEVONthink 2.x? DEVONthink 2.9 and later don’t create such groups on their own anymore (and if it’s empty it can be removed of course).
Probably yes, will delete.
Also, can I move ‘0 - Active blue’ to the Active inbox, same goes for the other groups?
None of them was created by DEVONthink, therefore it’s up to you 