View your usergroup table in Photopost?
If I go to your usergroup editor your usergroups seem out of whack big time.
Remember registered users in
VB is usergroup 2 and it seems to me looking at your usergroups that usergroup 2 is coppa which has no upload or comment permissions so this is what your problem is.
Your first group instead of being unregistered which is normal says Banned. I set this to upload and comments and logged out and as Unregistered it had upload link etc
So thus your issue if this was an internal install of Photopost that you tried to convert to VB3 integration. Am I close here

and the issue is the old usergroup structure was never dropped
To correct your problem delete every usergroup entry exept 6 which is admin and then do a usergroup refresh. This will ensure a proper import. Remember since on the import usergroup function we cache the entries that are already there so a user does not lose any prior permissions for groups already present. That is why when you change integration types which is never a good thing anyway you need to drop all usergroup entries except add the new integration admin entry so you can login and do a fresh import