Im not sure as to if you are asking how to make the player just walk up to a door and it open or if you want a player to push a key to make the door open? Either way a trigger box it needed. I am new to Unreal Engine so I dont know what exactly what you mean by connecting animations to triggers on the door but Ill show you video examples of both ways.
Walk up and door opens:
Actual Unreal Engine tutorial
- YouTube - part one
- YouTube - part two
Push button to open door:
This is my favorite way to make operable door, this was the first way I learned to make a push to open door. This guy has a good amount of tuts to learn with aswell all done very well.