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

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.

The plugin isn’t listed under VST3.
All Felt Instruments plugins are presented as VST2 instruments, which might explain why they don’t show under another format ;-) Please, see the guides below if you need help setting up your live preferences.

How can I enable a VST / AU plugin on a Mac?
Please, see this Ableton guide for help.

How can I enable a VST plugin on Windows?
Please, see this Ableton guide for help.

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, not the samples. Please, see this guide to learn how to install the plugin.