If the Plug-in Support has been installed correctly, you should be able to go to Studio One>Options>Locations and see a VST tab. If this is not the case, you may need to go to Studio One in the menu bar and sign out of the account that you are signed in as. You can then log back in with your user name, so that you are logged into the correct account. You can go to Studio One>Studio One Installation to install the add-on.
If you are having a problem getting your plug-ins to install, please take a look at these instructions:
1. Please open Studio One and go to Studio One>Options>Locations>VST Plugins and verify that you have the correct directory added to the list of folders that the program scans at startup. You want to add the directory that you have your plug-ins installed to. If you do not see the "VST Plug-ins" tab under the Locations tab, then you want to make sure that you have activated Studio One Professional or Producer or you have installed the VST, AU, and ReWire support add-on if you are running the "Artist" version of Studio One. Press the "Reset Blacklist" button while you are in this window.
2. Right-click Studio One and choose "Run as administrator" when opening the program to determine if there is a possible permissions problem.
3. Studio One will only load 64-bit plug-ins into the 64-bit version of Studio One. The 32-bit version of Studio One will only load 32-bit plug-ins. If you loaded your VSTs from the c:\Program Files (x86) folder into Studio One under the "Locations" tab, this is more than likely your 32-bit plug-ins. If you need to install a different bit-version of Studio One, you can do so by downloading the desired version from your my.presonus.com account under My Products>Software>Studio One.
4. If you are still having a problem, try contacting the manufacturer of the plug-in for information about updates, compatibility issues with Studio One, or possible workarounds.