It seems like it's won't be working on Safari for much longer. Info from 2 days ago "I can confirm that on macOS Catalina Developer Beta 1, uBlock Origin is completely removed as it is not using the MAS distribution method."
Src: https://github.com/el1t/uBlock-Safari/issues/151
This hasn't been updated in over a year (last commit Apr 2018). Personally, I use Wipr from the App Store because it's very cheap. AdGuard is also an option.
