To get around this storage access issue and launch games from ARC Browser in the latest versions of these emulators on Android 11 and later you need a small helper app.
- Download SAF Proxy 1.1 here and install it on your device.
- Open SAF Proxy and grant it access to your rom directory/directories.
- In ARC Browser, use the template for the emulator that has "(via SAF Proxy)" in the name.
- Make sure you're using the latest version of the emulator.
(This functionality will likely be integrated in ARC Browser in the future, but right now you need to use this app)