Your Windows VPS is reached with Remote Desktop (RDP) at IP:PORT using the dedicated RDP port and the Windows username in your welcome email.
Open Remote Desktop Connection (search "mstsc"). In Computer enter IP:PORT, click Connect, then enter your username and password.
Install Windows App (formerly Microsoft Remote Desktop) from the Mac App Store. Add a PC, set PC name to IP:PORT, save, then double-click to connect.
Install Windows App (iOS) or Remote Desktop (Android), add a PC with IP:PORT, and connect with your credentials.
Straight answers.
On our network your Windows VPS uses a dedicated forwarded port (in the 53000 range) on a shared IPv4. Use IP:PORT from your welcome email, not :3389.
NLA checks credentials up front. Re-enter exactly as in the welcome email (the username is case-sensitive). If it still fails, reset from the panel or email [email protected].
Today Windows VPS are sold on a BYOL (bring-your-own-license) basis — see the note on the order page. Ask support if you're unsure what you need.