To get floating licenses for Mathcad to work you need to install Flexnet on a license server. The most resent version you can download from PTC is at the moment (July 2020) 18.104.22.168.
And we really recommend having the license file available before starting the installation. If you don't have it, please contact us to get it, and then continue reading.
Go to support.ptc.com and log in with your PTC account. If you don't have any PTC account you can create it there. If you don't want to do that you can contact us and we will provide you with what you need.
After login you can scroll down and click on the 'Download Software' button:
Then expand the 'Additional Downloadable Software Updates' and click on 'PTC License Server: FLEXnet Publisher':
Scroll down and click on the 'English' button:
Then you should see the pdf that explains which versions you can choose between. So if your server is using a 64 bit Windows OS we recommend downloading 'Lmadmin 22.214.171.124 Installer 64 Bit' version:
(Note that this version requires "Visual C++ Redistributable Packages for Visual Studio 2013 (x64)". If it's not already on the machine it can be installed from:
Unzip it and run the setup.exe.
When you get to the third screen, you need your license file:
Don't use the upper part. Just drag-and-drop (or browse for) your license file in the Source field:
Then you only have to wait until you'll see 'Available' as the Status.