I have the same issue, I'm downloading the Linux file, but it says read-only? I own a 93.0.4577.107 (Official Build) (64-bit) Chromebook, as in the ones used for children's school, but I personally bought this one so it's not school-related.
Viewing post in Trying to set up on Chromebook
This sounds like a file permissions issue. I haven't done a whole ton with chromebooks, but you probably want to get linux running, here's a guide from google. https://support.google.com/chromebook/answer/9145439?hl=en Next you want to change the file permissions so that the file is executable. You do this by typing the command "chmod +x /path/to/your/file" in a terminal. You should be able to run the file by just typing in the file path and hitting enter. Best of luck and have fun!