Why there is no sound on keypress? (Or keep showing Loading message)

Windows: Install Visual C++ (download here) then quit and start Mechvibes again

MacOS: Go to Privacy in System References then check Mechvibes in the app list and restart the Mechvibes, or in the Application folder, right-click on Mechvibes and select Open instead of double-click

Why there is no sound when I play LOL (or other games)?

Try open Mechvibes with Administrator permission

What kinds of data does this app collect from me?

Nothing. What happens on your PC, stays on your PC.

How to add more sounds to Mechvibes app

You can download more sound packs here or create your new one, then follow those steps