The first time
After making sure Regroover is installed correctly,
open a new instance of Ableton Live and click Live on the top toolbar menu
Click on Preferences...
Click the File Folder tab
Use Audio Units should be On if you want to use the Audio Unit version of Regroover
Use VST Plug-In System folders should be On if you used the defaults during installation
Now click Rescan and close the Preferences window
In the Browser Sidebar
Click on Plug-ins
You should be able to see the main VST folder and the Audio Unit folder (if you enabled it)
Regroover Audio Unit
You will find Regroover inside the accusonus folder
You will find Regroover inside the VST folder
Tip : If you have many plug-ins installed, take a moment to look carefully in your plug-in list before panicking !
You can drag & drop Regroover in MIDI(Instrument) tracks, but not in Audio, Send, Return and Bus tracks.