If you are installing a Sound Set into Studio One 5 that you have downloaded from PreSonus Sphere, you will need to make sure that you are activated using PreSonus Sphere and NOT another copy of Studio One 5 that you might have in your account. To do this, you can open Studio One and go into "Studio One" in the menu bar of the program. From the drop-down, select Studio One Activation. Check the radio button for activating using PreSonus Sphere, press the "activate" button, and close/re-open Studio One. Below is a screenshot of this window...
For information on installing Sound Sets into Studio One, please take a look at the article below...