To diagnose a missing plugin in your DAW you should first check your plugin folders to ensure the files are in the correct location. That will be the following locations:
Windows:
C:\Program Files\Common Files\VST3
C:\Program Files\Common Files\Avid\Audio\Plug-ins
macOS:
MacHD\Library\Audio\Plug-Ins\Components
MacHD\Library\Audio\Plug-Ins\VST3
MacHD\Library\Application Support\Avid\Audio\Plug-Ins
You'll be looking for a file called Splice INSTRUMENT.vst3/.component/.aax depending on your DAW.
If you don't see the file present in these folders, run the installer again to restore these files and then restart your DAW.
If these files are present, then the next thing to check is your DAW's plugin manager. Please consult your DAW's manual for information on how to find the plugin manager.