...to the need to seek students with whom there is a "karmic connection"; the point is that the bodhisattva cannot always be helpful to everyone, and so one should direct one's efforts at those who are already predisposed to one.
...in order to identify individuals with whom there is a "fate-based affinity"; the key is that the bodhisattva cannot always be beneficial to everyone, and therefore one should concentrate on those who are already inclined towards them.