In some MMO’s, you can target party members directly, by pressing a F# key - usually F1 through F4, F5, or F6 depending upon the party size. I would imagine there’s something similar to that here.

If using a controller, can target party members by pressing Up and Down on the D-Pad, to scroll through the entire party.

Point being, you should not be point-click targeting party members. People outside your party, sure, but not people within it.