Had some complications on my end, but it's working. Thanks!
So, it turns out I had the package installed from the extras repo, not the AUR. Had a snow storm blow through and since my manjaro machine was at work, couldn't check anything for several days. Anyway, the AUR version was way out of date, so I didn't bother with that one, but the Flatpak version was up to date, so I tried that. No chance it could work and the notice on the listing is woefully inaccurate. It states that connections can't be made due to "default permissions." Apparently the author didn't consider that this implies that some combination of permissions would work. But it doesn't. Wasted quite a bit of time trying and I'm sure your logs on your end could tell you how many times it got authorized by OneDrive (but nothing ever took in the Flatpak version).
Anyway, got in yesterday and deleted the Flatpak version because the extras repo finally had the current version and that worked flawlessly. Didn't even need to reauthorize, it just worked. This morning I noticed that the AUR version, which had been several versions out of date, is now also up to date. So that's cool. I would have replied earlier, but my default ubo permissions disallow inline scripts and there had been a restart since my first post, so my smooth brain couldn't figure out why I couldn't reply and was looking around to see if the thread got locked.