There are simple steps you just follow. These are as follows.
Click on the download button.
Go to the download page and the download starts in a few seconds.
Now after completing the process of downloading go to the file manager of the android device and select the file which you have recently downloaded from hay day mod apk.
Now click on it, if it asks for some permission please click allow for further process.
After getting permission now you will be able to install your game.
Click install and your game will install.
Also please uninstall the previous version to download the new one.