I've run into a few specific different issues. 

First question: can you access this link in your browser on your machine? https://ftpfp.proseries.com/pub/proseries/2020/LICENSE.HTM

This should just display our license agreement.  For a few customers, we've seen that their router or firewall has decided to block anything from proseries.com.  That prevents "download next year's product", that prevents updating, that prevents login calls.

If you can access that link, then we need as much detail as you can provide. What is the exact error message you are receiving? And what happens if you try to download and run the installer directly, from one of the links below?

Professional: https://ftpfp.proseries.com/pub/proseries/2020/CoreInstallerTY20.exe

Basic: https://ftpfp.proseries.com/pub/proseries/2020/BasicInstallerTY20.exe