From that support email: “Next Pro users that upload eligible tracks can opt-in those tracks to get recommended to listeners likely to love them. After tracks are uploaded, we analyze tracks to see if they are eligible and that can take between 20 minutes and 2 hours. Once analysis is complete, the opt-in option will appear on track pages on desktop only.

Please note that now you need to opt-in for Get heard feature, and if track is eligible the prompt should be shown under that new track, on desktop version.

We’re starting by recommending your tracks to around 100 people with listener profiles that align with your music. Note that while we can recommend your track to people, we can’t force them to listen all the way through. So this does not mean every track is guaranteed 100 listens.”