If there is no working ASIO4ALL configuration available Jamulus will start with a popup telling this fact but with the only option to close Jamulus. There is no way to change the ASIO4ALL configuration. The only way out is to uninstall/reinstall ASIO4ALL hoping the defaults will work. Jamulus should not quit if ASIO is misconfigured.

See also https://sourceforge.net/p/llcon/discussion/533517/thread/777663cf94/#da0c