Windows Server plans come with Remote Desktop enabled out of the box. Your welcome email contains the server IP, the Administrator username and your initial password.
Connecting from Windows
Press Win + R, type mstsc and press Enter. In the Remote Desktop client, enter your server's IP address, then the Administrator credentials when prompted.
Connecting from macOS
Install Windows App (formerly Microsoft Remote Desktop) from the App Store, click the + button, add your server IP and credentials.
Connecting from Linux
sudo apt install remmina
remmina -c rdp://Administrator@YOUR_SERVER_IP
First things to do
Change the Administrator password immediately: press Ctrl + Alt + End inside the RDP session and choose "Change a password". Then run Windows Update from Settings.
For security, we strongly recommend changing the RDP port — see Securing RDP with a non-standard port.