Ubi previously worked with HitRecord on a campaign for Beyond Good and Evil 2, which sparked controversy over the developer's deployment of "spec work" (submitting work with no guarantee of payment) in a AAA project with abundant resources. At the time, Polygon posted a useful breakdown of the "#nospec" backlash.
Possibly in response to that backlash, the new Watch Dogs Legion campaign is very upfront about how the process works, with a dedicated video explaining how payments will be handled in the campaign. Ubisoft has essentially posted bounties for different types of songs (like "Aggressive Grim Punk Song" or "Teasing Funk Pop Song") that anyone can submit content for. It could be a whole song, just vocals, or a drum beat.
Each song is allotted a $2,000 payout. If a piece of content you made is chosen to be part of the final product, you'll be assigned a payout according to how much HitRecord feels you contributed to the song. In the completed Beyond Good and Evil 2 campaign, for example, some contributors were assigned hundreds while others got around $30. Contributors to Watch Dogs Legion can expect payment by January 2020.
Overall, it looks like Ubisoft is putting $20,000 into the campaign to ideally end up with 10 new songs for the game. That sounds like a pretty good deal for a game that likely costs tens of millions to develop.
Thanks, Rock Paper Shotgun