you hold the controller on the side where the rectangular buttons beside the arcade buttons are pointing left, and they are your page selectors. then the arcade buttons are mapped to the corresponding slot on the remix deck. 

its a very basic map to play a basic remix deck,i am working on expanding it and making it for all decks.

summary, 

hold midi fighter where rectangular buttons are on the left (cable is on the right)

rectangular buttons are your page selectors

the arcade buttons are mapped to their corresponding slot on the remix deck 

update 1.0.0:

-control of deck C by pressing the left bottom side button (when holding the controller as indicated).

no changes have been made to the launching of remix cells.