As you know that Cast to Firestick from MacOS is not possible without AirPlay, AirPlay feature is available on macOS devices that support AirPlay Mirroring, which typically includes newer Mac computers. Older Mac models might not have this functionality. Additionally, both your macOS and Firestick need to support the AirPlay protocol for this to work.
For more visit: https://thewebbings.com/how-to-cast-to-firestick/