It’s not a popup, it’s the message you get when you open the music app.

To quote the OP of that post:

Just to update y’all, I got the 45mm and loving it so far! However I haven’t been able to use Amazon Music on it. I attached a picture of the weird error I get.

If the popup came out of nowhere, or in an unrelated app, I could see how it could be interpreted as a scamming attempt.