Congrats on releasing your game! I like how you've implemented the interface sounds in it :) The title and transition effects are cool, too.
To answer your question – the free sounds pack contains a small selection of sounds (about 150) from a series of larger sound libraries (over 4,000 sounds total so far)
Viewing post in Shapeforms Audio Free Sound Effects comments
There’s even a walkthrough: https://www.youtube.com/watch?v=MNhVJ8bW29s