Pro Site error after signing up and paying

After signing up and paying at thrpy.io I get the following error:

Warning: array_diff(): Argument #1 is not an array in /www/wp-content/plugins/pro-sites/pro-sites-files/modules/premium-plugins-manager.php on line 328

WP 4.7.4
Pro Sites 3.5.5

Support access granted, but no FTP details given.