Sorry no reply before now. I haven't installed any newer MATLAB releases in a while (last one was 2012a), and for those the installer had a place to supply the license file -- no need to install Network License Manager first. (I'm the license admin, so I already grabbed the license file after this 2019b purchase).
The main issue I seemed to be having is that when I try to get the actual software, even using my mathworks.com login, I keep getting an error message that I could not connect -- and the posted workaround of disabling antivirus, is not an available option for me [I'm an admin on my desktop, but unsurprisingly, antivirus policies are controlled by domain admins, and I can't turn them off]. I managed to download the ISO via another browser, so now I'm trying to get a suitable ISO mounting utility [i.e. one IT approves] from local Marvell IT, then hopefully I'll be able to both install 2019b myself and also make it more easily available to others at the site.