Ok I need some help with NextCloud

What I'm trying to do seems very simple, but it's driving me crazy and I'm almost certain that this is why I gave up on this last time:

I want to have a folder on my Mac, where whenever I drop something in it, it syncs to the NextCloud server at a specified location, then I can DELETE it from my Mac, and it STAYS on the server.

The only option I seem to have is full sync, which essentially defeats the entire purpose of external storage. I *know* there has to be a way to do this, but having set it up a couple of different ways from both my Embassy side and from my Mac side, I always get the same result, which is really unnerving because having all my stuff get deleted is the very thing I'm trying to avoid.

Any help will be greatly zapped.