Please note that Regroover is not a standalone application! it is a virtual instrument plug-in that you can insert in an instrument/midi track in your DAW.
Once the installation is complete, you should be able to find Regroover in the following paths:
Mac
/Library/Audio/Plug-Ins/Components
/Library/Audio/Plug-Ins/VST
/Library/Application Support/Avid/Audio/Plug-Ins
Windows 64-bit:
C:\Program Files\Steinberg\VstPlugins\Accusonus
C:\Program Files\Common Files\Avid\Audio\Plug-Ins
Windows 32-bit:
C:\Program Files(x86)\Steinberg\VstPlugins\Accusonus