We wouldn’t advise setting up your salary to come into the prepaid account, I’m afraid!
In order for us to identify whose card a topup is meant to be credited to, we need a customer to enter the 9 digit number of the bottom left of their card as the payment reference. Typically, companies sending money won’t let you do that and without it you would have to contact us every time to get it credited!
The other potential issue would be if you were to hit the topup limit for the prepaid programme - we’d then have to return the money to your employer and it all gets a bit messy!
As @valbg mentioned, the best thing to do is sign up for a Current Account (if you’re on prepaid, click on the blue banner at the bottom of your app) and in a few days you’ll get a new card, which, once activated will give you your very own Monzo Bank account number and 04-00-04 sort code, which you can absolutely get your salary paid into coming from another UK bank!