Installing

Once you have installed the app you can always check for a new version by going to About screen from the Hamburger menu.

As this program is not available on the Google store you need to do a few things to install.
First thing you need to do is allow installation of non-market apps. You can Google how to do this but the link below is pretty good at explaining it.

https://www.tech-recipes.com/internet/android/android-allow-installation-of-non-market-apps/

After you have enabled non-market app installation fire up your phone / tablet browser and head to the releases page.
https://github.com/jakebullet70/OctoTouchController/releases (Download the latest version)
Or directly
http://sadlogic.com/octotouchcontroller2/OctoTouchController.apk (This will always be the latest version - link is case sensitive - use this on older Android devices that can no longer browse GitHub)
Or in the F-Droid repository in the izzysoft repo
https://android.izzysoft.de/repo/info
Install it.

Note: There are so many variations of Android the above steps might not work for you. In that case it is better to head over to a generic Android support forum and ask questions there on your specific Android version and how to install non-market apps.

Some support forums below.
https://forums.androidcentral.com/
https://androidforums.com/

Honestly, there are so many flavors and version of Android on many makes / models of devices it's impossible to keep up with them all. What works on my devices might not work on yours.