How to activate Studio 2021 on a new computer

Hi, I recently had to buy a new computer (laptop) and now want to set up my Trados Studio 2021 upgrade on the new computer - I installed it from the link on my account but I cannot activate it under my license - it just keeps showing the free trial version. What are the steps to do this? Do I need to do something with my old computer first (which barely works). Or do I have to install my old Studio 17 and 19 upgrade as well as this 2021 upgrade? Can you please help with the procedure to do this. I have the activation key for my license but it doesn't recognize it on this install on my new computer.

Thanks in advance for your assistance!