They appear to have made this comic free to coincide with the release of the film, even though it actually has nothing in common with the film story-wise.
Google Play Link: https://play.google.com/store/books/details?id=2E-nCwAAQBAJ (May need to use VPN to access)
Comixology Link: https://m.comixology.com/Superman-Batman-Batman-v-Superman-D…
comixology works but the google play tells me it isn't available in my country