My question is simple. Using Seren to watch movies, the streams are populated with many RD, but none of AD.
However, when I switch to Cinema HD,Nova apks etc, and stream the same movie, I find plenty of All Debrid.
Just a wild guess, but are you using a VPN? If so did you try turning it off so Real Debrid can see your IP address. The service is tied to your IP address. You only need to do this when paying with a credit card to activate the service. Additionally, when activating any APK or App on Kodi it’s best to turn off a VPN upon setting it up. You can turn the VPN on after initial set-up.