Yep. Paper for taper jointing. Put some easifil into the join push, the tape in with a narrow putty knife so the filler soaks into the tape and you have no air bubbles. Then go over the lot with more filler and a wider knife. You have to push pretty hard to get the filler to soak into the paper so it will end up pretty deep in the joint. Unless you are a pro you'll probably end up with the odd air bubble and loose tape near the surface. You can just cut this out with a Stanley and add some more easifil
The expensive stuff is noticeably better but you do get through it. New is better than old as it clogs very quickly. Buy a roll rather than sheets and just keep tearing off a new bit. The timing is key. Do it when the filler has fully set but still soft enough to be easy. IIRC about 10-20 hours later, although there is a pretty big window and it never goes that hard.
Generally I find it better to put on too little and then go back and fill it rather than putting on too much and having to sand a lot. It makes a lot of dust