sudo apt-get install libhdf5-dev hdf5-tools
the libraries are installed in: /usr/lib/x86_64-linux-gnu/hdf5/serial/libhdf5.so
the hdfview program in the 20.04 is broken. you need hdfview version > 3, which has to be built from source. building on 20.04 fails https://forum.hdfgroup.org/t/building-hdfview-3-1-2-on-ubuntu-20-04/7906/12