In this context "mandala" means "a living situation, with you in the center".

So "mandala of the ground" means to see things from the perspective of the ground (as defined in the text, ground is "the ultimate natural state of all phenomena, which is primordially of an enlightened nature within great purity and equality"). Similarly "mandala of fruition" is to see things from the perspective of Enlightenment (which is "perfect, total purity" attained when you "actualize this ground").

In this context "mandala" means "a living situation, with you in the center" or "a configuration of elements as seen from the inside".

So "mandala of the ground" means to see things from the perspective that takes "the ground" as one's living reality ("the ground" defined in the text as "the ultimate natural state of all phenomena, which is primordially of an enlightened nature within great purity and equality"). 

Similarly "mandala of fruition" is to see things from the perspective of Enlightenment (which is "perfect, total purity" attained when you "actualize this ground").

In other words, the text talks about shifting your perspective, the way you see and construct your reality.