For security reasons, all connections need a username and password.
ApplicationServer XG is used if you would like to publish applications (i.e. have only access to particular windows applications on your android device) or you have multiple machines/VMs you want to connect to. If this is your scenario, then you have the correct software installed and can create a connection to your main PC by:
1. On the server: adding the main PC "desktop" to the list of published applications and pressing "apply"
2. On the client: create a "2X ApplicationServer XG" to the main PC and enter the username/password for the account you would like to sgin in as.
If you have no need for published applications or have only a single PC, then you can use the RDP functionality of the client to connect to the built-in RDP support provided by your Windows PC. Again, the username/password are the same as the one you use to sign into your PC.