Having the same problem when opening Kami assignments to grade on my iPad through the Canvas Teacher app. I was able to open the Kami assignments through the Canvas app and write, etc. with no issues. I opened it today on my iPad to get some grading done, and kept getting a similar error message when I was asked to authenticate my Drive account.
I can open Kami assignments everywhere else (laptop, Chrome browser on iPad) with no issues, and I can open non-Kami assignments in the Canvas Teacher app.
I know there was an iPad update recently, as well as a Canvas Teacher app update. Wonder if this created some kind of “perfect storm.”