Since your question does not really concern uLaunchELF (aka: uLE), but rather the project "Free McBoot" (aka: FMCB), I suggest that you restate your problem in the forum dedicated to that project. You will find it under the name "FreeVAST", which is an older name of the project.
When you do this you should remember to describe exactly what version of the installer you used and how you went through the installation, including your choices for any variable options. Note that some versions of the FMCB bootloader do not include any USB support, so that might explain your problem.
Best regards: dlanor