You have to look for the build natively Purchases element and put that on your page. Make sure that you call this to set the ID BEFORE your customer makes a purchase or calls the RevenueCat API. As soon as you let anywhere in your app call the RevenueCat API without setting the user ID first it will assign a revenuecat ID.

Also look into RevenueCat aliasses as it will add as many ID’s to a user as you or another process adds. So you will find an array of user ID’s from the past and current one. So you can add to any user the ID (for instance on login you can always check if there is the bubble user id in there or not, if not simply call the Purchases element and add it).

Look at this link for youtube tutorials for more information: Setup RevenueCat App | Natively Docs