C20 installation hangs on software license agreement

I am completely stymied in my quest to update to C20. I can follow the link from the update purchase record in my account to download the C20 dmg and then open the dmg and install it to my App folder. When I then try to launch the app I get a splash screen to agree to the software license agreement on which the "agree" button is greyed out and cannot be selected. The "print" and "cancel" buttons are active. I have repeatedly uninstalled C20 and restarted my MBP. Gave up on this before Christmas in hopes and update would solve issue but 20.0.1 gives same result. FWIW, I am running OS 10.14.6 on a 2.5 GHz Core i7 MBP and having no other software or hardware issues. My support request to Phase One was only answered with a cut and paste response that showed no human had read my message. Would greatly appreciate any tips for dealing with this.