Thanks @mrmarkuz .
I was able to get Collabra to start up and edit documents in NextCloud!!! So that has been solved also. Again, thanks for your help.
It is really quite slow compared to the NS7 NextCloud Collabra. I suspect this is due to my Nextcloud & Collabra running on a hard drive rather than the original SSD.
Once my daughter has cleaned up the ~120GB of duplicate photos and videos that he mistakenly uploaded twice prior to the migration, (and was the cause of moving the instance over to the hard drive during the migration), I should be ready to move the images back onto the SSD. At that point I will be back to code on the SSD and data on the hard drive.
Now onto the rest of the outstanding issues.