I found Fixes #36003 - Migration error 'column settings.category does not exist' by stejskalleos · Pull Request #778 · theforeman/foreman_remote_execution · GitHub which should be the PR that fixes your problem.
From what I see, this has only been part of remote-execution plugin release 9.1, but Foreman 3.6 only ships 9.0 as of now.
9.1 seems to only currently be in nightly repos.
You could try and install 9.1 from nightly manually, though I am not very firm with deb basted distros and don’t know if or how that actually works.
I am not entirely sure if 3.6 is still in release-candidate stage or not, but I will link your post in Foreman 3.6 release candidate feedback to raise some eyes on this so it can be properly fixed.
