EXWM has moved to the new location https://github.com/emacs-exwm/exwm. The wiki is now available at https://github.com/emacs-exwm/exwm/wiki. The move was necessary since the EXWM author Chris Feng has been missing for a few years and new maintainers were added to the EXWM project. EXWM is currently maintained by Adrián Medraño Calvo, Steven Allen and Daniel Mendler.