I heard back from tech support and was directed to this article: https://support.presonus.com/hc/en-us/articles/115005456483-Installation-Issues-with-Universal-Control-on-High-Sierra-Mac-OSX-10-13?source=search
I'm running Mac OS Catalina, and even though the article is about High Sierra, the process works on the newest OS.
I followed the article procedures as described. The Quantum 2626 is now good. Universal Control now has access to the interface. Mac’s system preferences allow the device to be selected under “sound,” and the 2626 is now an option in all DAWs. The formerly flashing blue light on the Q2626 now solid blue.
I know "zelousrecording" started this thread about their PC. Apologies. Didn't mean to hijack this thread. However, if Window's security is throwing up a roadblock, it might be that Presonus' Knowledge Base (KB) has instructions that will resolve the issue filed under an older version of the Windows OS. That was the case here for the Mac OS--would not have thought to search the KB for High Sierra issues and solutions.