The windows client has a ‘Start with windows’ option in the settings that starts Icedrive minimized and with the virtual drive mounted, but there is no equivalent option on the Linux version.
After a little trial and error, I found that starting the Linux appimage with the ‘-startup’ option provides the same functionality so it can be autostarted on logon in the background. (at least on manjaro it does, maybe the same on mac).
That didn’t work for me on Linux Mint 22, but going through the settings menu does.
System Settings → Startup Applications → + sign → Custom Command
Name it IceDrive and for command just put: /home/ko4fzg/Downloads/IceDriveMounted-v3.whateveryourversionis or wherever your IceDrive is located