APK expansion files

My Android APK will be bigger than 50mb when I come to put it up on the Google Developer Console. I understand I’ll have to use Expansion Files but don’t know how to go about it. Is there coding involved or can I literally just .zip the files? I’m a little lost

The First APK file can simply be a ‘Placeholder’ which may handle the installation etc of the expansion file. The expansion will actually contain the game.

Buy Game.
Download Game.
“GameX additional files required”.
Download Expansion APK.
Play Game…finally. Or something like that.

But on the whole the Second download might not be required

On most devices, when an application
is installed, expansion files will be
downloaded along with the APK and will
be saved to the shared storage
location (the SD card or the
USB-mountable partition) on the
device. On a few older devices, the
expansion files may not automatically
install with the APK. In these
situations, it is necessary for the
application to contain code that will
download the expansion files when the
user first runs the applications.

Taken from here