If you are installing a floating license for 6.1 then you will need FlexNet Licensing Server software, available for free from PTC. You then need to obtain a license file to install into FlexNet. This license file will contain the licenses that are made available to client applications (such as your Styler).
For the license file, the hostname should be a name that identifies the server to yourself or your company's administrators. The actual server name is a good idea. The Host ID is the important part to get right. The Host ID is the MAC address of your server, and the easiest way to generate this is to use the cpu_id.exe tool supplied by PTC. Note that you will need to run this on the licensing server machine, not the Styler client machine. This will get you the Host ID of the server in the form 00-11-22-33-44-55.
Once you lodge the request with PTC you should expect an email with your license files within 15-20 minutes.