What specs should a Windows RDP have?

At least 2 vCPU and 4 GB RAM; 6 GB is comfortable for a browser and a few programs.

How do I pay without KYC?

With crypto, at a provider that only asks for an email or messenger account.

Is the Windows license included? Some prices cover only the server. Look for the words licensed or included.
What does the cheapest plan really have? 1 GB of RAM runs Windows badly. 4 GB is a sensible floor, 6 GB is comfortable.
Which coins, on which networks? USDT exists on several chains. Send on the network the invoice shows.
What happens if you underpay or pay late? Good checkouts show “partially paid” and let you top up.
What is the refund rule? Crypto can't be charged back. Expect balance credit, not money back.
Where are the servers, and is support reachable? Pick a location near the service you connect to, and check support answers before you need it.