I suggest you look at the reply I made last night to someone asking about this, where I not only posted the server side screenshot you have, but the corresponding client side context menu when this is enabled.
https://forums.urbackup.org/t/can-client-trigger-urbackup-himself/13015
The problem is, and I’ll say it again, that even when the above is in place on the server side the server does not seem to be honoring client side changes.
I need to do more testing to confirm/refute that, as I wanted more information before doing so. One has to get one’s proverbial ducks in a row and know how one expects something to work (as the designer says it should) as a prerequisite to doing thorough testing.