Google makes "beta" apps available through a web link we give you (see below).
Google knows who you are by the Gmail address you have registered with the Google Play account on your Android phone.
(because you gave us that Gmail, we have added you to the list that can download the "beta" app.)

Select this link to the Android "beta KidPrint":
          https://play.google.com/apps/testing/org.yottainnovation.kidprint