Apparently with a gimbal and some fast-moving mirrors.

https://www.ll.mit.edu/news/lincoln-laboratory-laser-communi...

I was wondering about this too! I did not know how they can aim a laser from so far at a moving spaceship.

I generated this visual map about to help me understand it - https://vectree.io/c/aiming-space-lasers-gimbals-and-beam-di...

Just like this, a Starlink gimbal being tested for future third party laser comms: https://www.youtube.com/watch?v=dpFfC9WY0qs