Incompatible Version means that you're trying to run a plugin built for a different version of Rockbox. Make sure to replace all files when updating Rockbox.
"Missing Base Wad" indicates that the plugin isn't finding the IWAD where it expects it. Rockbox Utility can install the Freedoom WAD for you, I believe.
I have seen a lot of complaints about not enough RAM with the Fuzes. Even if you overcome these issues I can't guarantee the plugin will allow proper game play.