I'm trying to set up cross-platform saves between Steam and my Switch. I get logged in fine and click allow, it swaps from browser back to the game, and then I get this error: Screenshot

Any suggestions? I haven't started playing it on either platform yet, so I can do anything needed without concern for losing save data.

Support got back to me over the weekend, which was pleasantly unexpected. Turns out to do the sync, you need to create a save game on the PC side before trying to set up syncing on the Switch. Works like a champ now.