After you have installed the MangoSign player from the App Store, the first thing you will want do is to open the Startup Folder within Windows. 

To open the “Startup” folder the easy way, just hit Windows+R to open the “Run” box, type “shell:startup,” and then press Enter.

You should now have the Startup Folder open. 

Next, simply find the MangoSigns app icon through the Windows bar in the bottom left hand corner and Drag the MangoSigns icon/logo(left click/drag) into the Startup Folder.

This should have created a shortcut for the MangoSigns app to the Startup Folder. Now the next time you reboot your computer, the MangoSigns player should automatically launch.

You can also try the latest MangoSigns Windows player installer which can be found here