How to install geneticbikes.com's chain tug to horizontal dropout with anti-rotational washer and hub gears?
The extra stud would usually sit in the dropout slot and help align everything, but your dropout runs the wrong way for that so the stud is just an annoyance. File it off and things will work much better.

If the raised/recessed circle on the front of the tug is not big enough to accept the nut on the hub you may have to file that as well. It's visible in the bottom photo above.

update: you will probably be ok with only one antirotation washer, but ideally if you can get the tug in between the frame and hub so you can put the washer on the outside that would be better. Remember that the tug is now taking the force from the chain so the nuts don't need to be done up especially tightly. So you don't need full thread coverage on the nut.