Hi -> Open setting search for Install apps -> you will get "Install unknown apps" or "Installunsecure app" -> tap it and tap firefox and turn the Allow from this source to on

You can install apps from firefox Beware of unsecure apps only install if you know what you are installing hope it helps.

1. Download the APK you want to install.
2. Navigate to your phone settings menu then to the security settings. Enable the Install from Unknown Sources option.
3. Use a file browser and navigate to your download folder. Tap the APK to begin the installation process.
4. The app should safely install.

Hi -> Open setting search for Install apps -> you will get "Install unknown apps" or "Installunsecure app" -> tap it and tap firefox and turn the Allow from this source to on You can install apps from firefox Beware of unsecure apps only install if you know what you are installing hope it helps,

thanks For a fast response its help me my issue solved.