Windows store version:  Can't put a shortcut on the desktop; can't find the install directory so I can go there to create a shortcut to place on the desktop; can't get it to work with Firefox even after installing the EnpassNMHost_v5.5.1.0.exe. 

So, where do I get the "old style" desktop version I was using before Microsoft scrambled my system with an attempt to force an Office 2016 replacement of my Office 2007 suite?  (I had to rebuild my system and when I went to download Enpass, it appeared the MS Store version was the only one I could download. )

Do I need to uninstall the MS Store version to get the desktop version to work?

IMHO, the MS Store version was a VERY BAD idea.

wmc

Yes, you need to get the bridged version. However it does not support Windows Hello yet. The bridged version can be found in the Windows Store also. That is my experience. I just purchased the UWP Store version and that will be going away apparently.