It's normal these days to cross-assemble, typically running your editor and assembler on a PC or laptop. But for a more authentic experience you might seek out a native assembler for your platform of choice: Merlin and ORCA/M are popular (were popular) on the Apple II. (You might need to search a bit to find a copy.)
I'm coming to this conversation late, but for what it's worth, ORCA/M (and all the other ORCA tools) are still being sold as part of the "Opus ][" collection from Juiced.gs:
https://juiced.gs/store/category/software/
Juiced.gs also sells a product called Golden Gate which allows you to run the ORCA tools on a modern computer. It's an application-level emulator, rather than a system-level emulator, so disk access goes directly to the native filesystem. (So you can essentially use ORCA/M as a cross-assembler.) I haven't used it myself, though.
Personally, I am enjoying using ca65 so far, and I would recommend using it. But, I just wanted to point out it's easy to get ORCA/M if you want it.