I did reproduce the denied message, although with a completely different file (a long chain of alphanumeric characters).
The message has nothing to do with the issue.
After installation, the downloads preference is set to “Always ask me where to save files”. The default downloads directory is “~/tor-browser_en-US/Browser/Downloads”.
Reflected the change in the profile, modified permissions in Browser directory, it should work.
downloads directory · troubadoour/apparmor-profile-torbrowser@295e1ae · GitHub