To get this trophy, you just need to close 75 rifts across the larger map areas.
There are more than 75 in the game - I think there are 87 in total as the trophy dropped for me after closing the last rift in Emprise du Lion, and at that point I'd closed every rift in every area except the Hissing Wastes which has a further 12.
Note that if you are also attempting to get the Demonslayer trophy (for killing 1000 demons in one play through), you may not wish to close every rift until you've earned that trophy - attempting rifts, getting a few kills, then abandoning the rift by running away is a good way to farm kills.