Trying to setup gmail on an ipad using a g-suite legacy domain. Get an error: "g suite access is disabled on this device"
Went back and forth in a Google support forum and found the answer.

The documentation (perhaps wrongly), pointed me at the "IOS settings" under Domain Management -> Device Management as the place to fix this.  The problem is that Legacy Domains do not have this feature and it's greyed out.

However, If you go to Device Management -> Setup -> Sync on Mobile, there's another feature called "IOS Sync".  Turning this on was enough to solve my problem.

iPad is now working perfectly with Gmail and Google Docs.