1974 Schwinn Continental Info

Bike sat for 8 years outside while I was away. I finally came home and started to work on it. My issue is this freewheel or cassette. This is where I got stumped.

I read this is threaded on by that star locking nut, is this true? Amazon has cassettes for around 50$.

Could I replace it with a aftermarket cassette?

Any and all information is appreciated ,first time disassembling a road bike.