(I have cropped out computer ID)
When I click on the Activate button, it attempts to launch firefox but nothing happens later. Also even if firefox is already open, no website is being opened.
That's rather obscure.
I doubt you'll be able to get LabVIEW to work with an odd version of Linux. I believe LabVIEW is only guaranteed to work with one or two of the common Linux distributions.
Progressed a bit further while using Chromium browser.
I have redownloaded and tried it as said in the window.
People were reporting a lot of problems recently getting LabVIEW activated on regular OS's. It turns out that there was a flaw in the activation system that if the person's IP address wasn't IPv4, they get error dialog boxes saying "check your internet" connection.
See if this thread helps you. https://forums.ni.com/t5/LabVIEW/Labview-Community-2020-Edition-Activation/m-p/4128198#M1188961