Keyboard Installation Instructions
The first step places the keyboard layout file in a folder where the system can find it.
Open the folder:
and paste the file there (enter your password when prompted).
Restart your computer completely.
Without a restart, the keyboard isn't available to the system.
After restarting, the keyboard is available,
but it still isn't installed.
Go to → System Preferences → Keyboard,
and choose the "Input Sources" tab.
Click the + in the lower left corner and select the new keyboard.
Then click "Add".
Also, check the box "Show Input menu in menu bar".
This adds an icon to the top right of the menu bar,
which lets you select different keyboards in any application.