> Port 5000 is in use by another program. Either identify and stop that program, or start the server with a different port.
An instruction on how to specify port would be nice.
The docker-compose.yaml file is where you specify the ports you want to expose. It looks like by default it's 5000:5000 (5000 outside and inside the container). You will need to change it and then run docker-compose up -d.
You can change it to something like 5133:5000 and access the instance through localhost:5133
The output of that tool also looks suspiciously like a so-called cryptomatte which many 3D tools use to store masks for each of the objects/materials/etc, Blender can read and write those — although I am not sure whether this tools supports outputing those.