When setting up Quicklaunch on a room PC, the application runs under a user account. You do not require a Windows Domain joined PC if you are using Quicklaunch Standard Edition, but the enterprise functionality used in Quicklaunch Ultimate Edition requires the account used for installation to be joined to a Windows Domain in order to use Skype for Business integration.
For Quicklaunch Ultimate Edition, we recommend you use the same account for the Quicklaunch room account and Skype for Business integration, but there is no strict requirement for you to do so other than to simplify setup.