Hello Fearless,
You don’t have to create a user, as NoMachine uses a system user that is already created on the server side (System username and password).
While it is common on Windows not to set a password, one must be set if someone wants to use NoMachine (this is for security limitations).
You can find more about this subject in the following article : https://knowledgebase.nomachine.com/AR05L00802
We remain at your disposal if you have further questions or issues!