This info on the page is outdated.
Pinging @Manoj.
Because you are on /e/OS R (Android 11).
Rooted debugging was discontinued in /e/OS based on earlier Android versions in favour of passing SafetyNet.
You would get Rooted debugging back by upgrading to a dev build based on Android 12 (S), but I don’t see that option currently for your device.
For details see … SafetyNet on /e/OS Community "dev" devices - let it in or not?