This appears not to be working:
Ubuntu 18.04 LTS
Waterfox 56.2.0 (64-bit)

I get the "One more step" page and "Check Connection" returns "Cannot find the native client". I have tried it with /usr/bin/google-chrome, /opt/google/chrome/google-chrome and blank for the native client (/usr/bin/google-chrome is in the $PATH).