It seems this is a hosting problem, not with Machform.
(1) the "Undefined Index" PHP error could be due to your hosting using an old PHP version.
(2) "there was a problem connecting to your web server" could be some sort of internet connection problem e.g. your internet provider or your host.
Since the forum here is for general discussion and minor problems but not specific tech support, suggest you log a ticket with Appnitro.