The tensioner is built into the frame. Achieving tension is spinning an Allen wrench. Getting the right tension can be done several ways. It would help to have a briefing about it before you started taking the wheel off, but it’s easy to do. I can’t figure how cog alignment would be a problem.

on my bike the tires were stout, the culprit was a too cheap machine wheel build that went taco.

”Overstated, but some merit...” lol BikeForums in a nutshell