Download the APK file here:
If there is no browser window popping up after the download has finished, you have to manually open the apk file.
Normaly this file can be found in your downloads folder.
Click the apk file in your file explorer or the 'open' button of your internet browser and follow the installer.
If it worked, you can stop here, otherwise continue.
Open your device settings and open either 'Security', 'Lock screen and security' or 'Biometrics and security'.
Here click on the entry for 'Install unknown apps' or 'Install other apps'.
There find the browser or explorer app you are trying to install clickr with, click on it and enable 'Allow from this source'.
Sometimes, when you are updating clickr in another way than it was installed a 'Not installed' message can pop up.
To fix this you have to uninstall the old clickr app first.
But don't worry, your scores won't get deleted. If you are connected to a network while tapping your score is backed up on our servers.
If you can't get it running after all that help, feel free to ask me via firstname.lastname@example.org.