How does a client authenticate a RADIUS server vs How does a Radius server authenticate a client?

So here I am, trying to connect to a radius server after lectures on radius servers. The professor skipped on how a client verifies that the server is authentic and not a ‘rogue access point/evil twin.’

More in depth question: How does one protect themselves from this MITM attack if they have never connected to said networks WiFi RADIUS server vs if they have before?

TUIA!