Canelo vs GGG 2 is available for purchase on the FITE.TV website at the standard HD event price - $84.99 USD. You can buy the event on web and watch it in any of the FITE apps (including iOS, Android, Roku, and Apple TV), as long as you sign in with the same account. The price on the app stores is $99.99 USD because of the significantly higher transaction fees app stores are charging. Also, Canelo vs GGG 2 is not available to purchase with FITE credits.
After the purchase you will receive a FITE confirmation with an Order ID on the email associated with your purchase to make sure you are informed that this is the email you have used. On that email will be all additional info on how to access your purchase quickly and on how to test your set up before the big fight.