Please make sure you are using Ableton Live 10.1 or higher to use VST3 plug-ins.
You need to go into the folder
C:\Program Files\Common Files\VST3
and change the name of the folder
In Live open the preferences and select Rescan
Ableton Live will now see the plug-in.
Please note if you changing the name of the folder stops the ARA mode of VocALign Ultra working in Cubase and Nuendo.