The best way to make modifications to your account is by creating a support ticket in your account portal.
- Login at https://portal.macstadium.com/login
- From here, you can view your subscriptions and open support tickets
If you just opened your account and are trying to access your new machine, login to your portal account and look for a ticket titled "Installation" which will contain instructions on how to connect to your new server.
Updated about a month ago