Custom parts for UR@B boards not in KiCad
Add the path to urbparts.pretty/ to your project's Footprint Libraries.
Add the path to urbparts.kicad_sym to your project's Symbol Libraries.
Open up Footprint Editor > Preferences > Configure Paths... and add an entry under "3D Search Paths" with "urbparts3d" for Alias and the full path to urbparts3d/ for Path.