The "racket -f as.scm" is supposed to be done in your terminal, you're right! DrRacket is a different thing that is very cool, but not the tool to run Arc with.
When you type it in your terminal, what does it say? If it says something like "racket not found", try downloading the racket installer from https://download.racket-lang.org/.
If it installs correctly, you should be able to type "racket" (without quotes) in your terminal, and get a message "Welcome to Racket 8.0". To quit, press Ctrl-D, or type (exit) with the parentheses, then hit enter.
If that works, you should be able to run "racket -f as.scm".
Thank you so much, zck :)
I've used a combination of your helpful suggestions, stack overflow, and cd command to get to the right folder, and now it works. I got the arc command prompt (arc>) in my terminal now. I will take my time to explore the tutorial on Arc.
I feel good that this community is really helpful. Thanks everyone!