Ubisoft Connect asking to activate CD Key on Startup?

Hello everyone,

I'm having a strange issue with Ubisoft Connect on my Deck. I followed a guide to add the installer as a non-Steam game, install it, then change the target to the correct compatdata path so the program launches.

However, after I logged in, it immediately opened a prompt to activate a CD Key. Cancelling or closing with the X button at the top makes the menu go away, but then the app just runs without any further prompt until I hit Stop in Steam. There doesn't seem like there's any way around that prompt and I can't continue to install any games. I'm trying to install my Ubisoft Connect copy of Assassin's Creed: Revelations if that makes any difference.

Any help would be greatly appreciated!