You do not. Tor browser is just a browser and proxy baked together for convenience. You can use any proxy and any browser you want.
Actually, tor is also not browser centric at all either. It does TCP (if not more), so any protocol will do. Proxy is typically a SOCKS interface IIRC, so any client will often do as well.
Actually, tor is also not browser centric at all either. It does TCP (if not more), so any protocol will do. Proxy is typically a SOCKS interface IIRC, so any client will often do as well.