Drag the Adorage item from the transition's list [A] to the timeline [B]. Drop Adorage between the overlapping area of the both clips (as you know from Premiere-internal transitions). After the effect is assigned, press "Custom" [C] to customize the effect and/or to get the effect list of the installed Adorage effect packages.
Following [Images #2, #3] shows: how to create overlapping clips
Overlapping clips requires trimmed clips. Trim left clip at the right end and the right clip at its left start.
Move the right clip to the left to create the overlapping area.