I had a similar problem. Here's the fix for most Macs. You have to manually allow permission for the Mac to install the Driver. Steps are below.
1. Make sure you've downloaded the latest version of UC and the Quantum Thunderbolt driver (from the Quantum 2626 downloads page on the Presonus website.)
2. Go to "System Preferences" (Click on the Apple in the upper left of your screen and click on System Preferences.)
2. Click on "Security and Privacy" icon
3. Click the pad lock in the bottom left of the window and enter your password.
4. Towards the middle lower part of the window, it will ask you if you want to allow permission to install the Presonus Thunderbolt driver (or something like that.). Click "Allow."
5. Restart your computer and try again.
6. If still no luck, Turn off your Quantum 2626 and unplug it from the power and Thunderbolt.
7. Turn it back on and try again.
If it takes more than that, I don't know the answer.
Best of luck.