Solved...
"You need to manually create the path as follows: click on your hard drive icon, then ... Users, Shared, Library, Application Support, then create a new folder called Presonus, open this folder and create another called Presonus Sphere and try activating again."
Yep, that worked for me. In my case, I didn't have the "Application Support" folder. I had to add all of the following:
...Application Support/Presonus/Presonus Sphere
Why can't Presonus figure this out?