iCloud error “insufficient disk space” but there should be plenty of room

On iOS with iPhone Xs running iOS 12.3.1 and Devonthink To Go 2.7.1. I started the database on my iMac. Sync to my iPad fine. My iCloud storage has more than 1TB avail and my iPhone has more free space than the iPad - about 185GB free.

So is there something else that can cause this error? I couldn’t see how to troubleshoot so any suggestions are welcome. Two other smaller databases synced to the iPhone without a problem.

DEVONthink To Go is trying to determine if a database you download will fit on your device. And using iCloud means you’ll need more than just 1× the disk space because iCloud first downloads files, then DEVONthink To Go gets them for processing.

How large is the database you’re trying to download in total?