Did you used horticultural vinegar or household vinegar?* If you used the household vinegar and the weeds were established, that could be the reason you didn't see much results.
So the ground cover will still grow if I use newspaper in between and mulch?
Yes, if you either surround your plants with it or puncture holes in the paper when you plant.* By the time the groundcover is mature enough to spread, the newspaper will have decomposed.
Once it's established I guess I won't need the mulch anymore but for now.
Correct
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.