Please, check if the drive letter Z is available on the Viewer PC. This drive letter is temporarily used during update operations in the Remote Install tool.
Perhaps, the license key text was garbled or something. Anyway, I identified you as a paid customer and manually raised your support level. Feel free to submit a support ticket now.
You might want to enable notification panel in the Host settings. Here is how https://www.remoteutilities.com/support/docs/notification-panel/ . Note that in the latest beta version 6.9.0.1 this check box is located on the "Interface" tab in the Host settings window.
We need to isolate the issue first. For example, we could set up a Host on our testing machine , point it to your ID server and leave it working for a while as well as give you access to that Host. You could see then if the connection is stable or not.