I would suggest just removing it. Debian/Linux have a system wide update mechanism for everything - the OS & apps - and it's very strongly preferred that you just use that.

The UX of asking stuff during install is also pretty bad - and goes against the grain; it's vanishingly rare that Linux install packages ask questions. Even if you make it a startup/in-app/config option, it would also be a strange question to ask on Linux:

Would you like auto-updates? Of course, everything on linux auto-updates, why do you ask? No - I mean would you like me to force-update just fman everyday? What? No!

Also, don't forget to update this page while you're at it: https://fman.io/docs/obtaining-updates

Done. fman 0.3.1 is out. Per your suggestion, it just removes the cron job. I wrote an apology [1].

[1]: https://fman.io/blog/an-apology-to-linux-users/