These are the steps I followed to install k4a-tools, libk4a and libk4abt on Ubuntu 20.04. The general steps are as outlined in https://docs.microsoft.com/en-us/azure/Kinect-dk/sensor-sdk-download, with a couple of hacks to make things work on 20.04. - use of 18.04 repo, even though OS is 20.04 - installed lower versions of tools and libraries (as latest versions of sensor and body tracker don't seem to be compatible on 20.04)
sudofor hardware access)
simple_3d_viewerto verify body tracker works.
~/libs/lib. You can then perform an equivalent command as above.