how in the fresh hell do i get in here

[Kosta]

I accepted these quests and I can't finish them because idfk how to get here

[Thicc Stoccpot]

At what level/mission of the main story are you in? To get to mushin tower you have to complete act 3 first. Then open your map by pressing "m". Choose "moonwater" and mushin tower should be there at the right side of the map near the bottom. The main story forces you to go there which is why I think you haven't even completed act 3 yet.

 

As for tower of infinity - it's inside mushin tower. In order to get in you gotta reach level 50. Then you read the quest letter in the quest menu by pressing "j" and choose quest letter tab.