https://www.cnet.com/science/space/nasa-holoported-a-doctor-onto-the-international-space-station/

Basically, high-quality 3D models of the holoporters were developed, digitally compressed, transmitted and reconstructed in the spaceborne lab -- all in real time.

Meanwhile, a mixed reality display aboard the ISS, namely Microsoft's HoloLens, allowed both the holoporters and astronauts to see, hear and interact with one another as though they were in the same physical space. Astronaut Thomas Pesquet, for instance, had a two-way conversation with Schmid and De La Pena right in the middle of the ISS despite being miles upon miles away from the holoporters.

The trio even holographically shook hands.