The fonts must be added to the Java Runtime Environment (JRE) that ships with MATLAB (if that is the Java version being used by the program). Below are steps to install the fonts:
1) Copy the TTF fonts to "<matlabroot>\sys\java\jre\win64\jre\lib\fonts",
e.g. "C:\Program Files\MATLAB\R2019a\sys\java\jre\win64\jre\lib\fonts"
Note: You might need to be an administrator to copy files to this folder.
2) Restart MATLAB.
3) You should now be able to see the Ubuntu fonts in MATLAB's font preference panel.
Note: If using the default JVM shipped with MATLAB, you must do this for each MATLAB version installed.
