You will first need to complete Trust CA - OS for your device before continuing.
This should work equally well in Firefox, Firefox ESR, or Librewolf.
If you are attempting to set up Firefox on Android, click the “Android” tab below for Android-specific instructions.
Open Firefox and enter
about:config in the URL bar. Accept any warnings that may appear about accessing advanced settings.
Search for security.enterprise_roots.enabled and double click on false so that it turns to true:
Now restart Firefox and you should now see this symbol indicating a secure connection:
To setup in Firefox Beta or Fennec, tap the kebab menu, then go to Settings > About Firefox Beta and tap the Firefox logo five times until it says “Debug menu enabled.”
Return to Settings > Secret Settings and enable “Use third party CA certificates”.
No additional configuration for iOS is required.