If you can’t see the plugin in Ableton Live, here are a few things to check:

Make sure you’ve downloaded and run the plugin installer  before proceeding.

I can’t see any of the Felt Instruments packs even though I installed them:
That’s because Felt Instruments are plugins, not packs. As such, should be able to see them in the browser under Plug-ins.

I’m on Windows and I can’t find the plugin listed.
Please, make sure you’ve installed the plugin to the plugins folder configured in your Live preferences. By default, it should be somewhere in your Program Files.

Note, though, that this is where you should install the plugin (the part you get from the Installers page), not the samples (the Pulse bit).