I found the solution at http://www.slipstick.com/outlook/links-wont-open-in-windows-10/. Files are there to auto-add the single line in registry that solved the problem - there are two choices - open...

This is the way to solve the problem -- it turns out that some distributed PDF forms REQUIRE using the free Reader DC and will not work with the paid-for Acrobat Pro. When both are installed it was a...