To get this font to work with MATLAB, you have to load the TTFs into the MATLAB JRE font directory as described in this link at Mathworks.

To use this font with MATLAB for Windows 10 64-bit:

1. Load the font TTF files into: MATLAB\<ver>\sys\java\jre\win64\jre\lib\fonts
2. Restart MATLAB
3. Change the font in Preferences -> Fonts as you wish

This was confirmed working with Windows 10, MATLAB2020a 64-bit on with Fira Code v5.2.