Can you tell me what error messages you are getting or what happened when you installed on your XP machine. We do have a TR open on XP but it is related to the running of sessions on an XP NoMachine server (https://www.nomachine.com/TR02L04266).
If you want to just install a client, you can install Enterprise Client. Scroll down on this page https://www.nomachine.com/download-enterprise to Enterprise Client.