Wiring for grounds wire in light fixture
That's a strange ground clip on the electrical box. The box doesn't appear to be metal and that clip will interfere with your fixture bracket. I would remove that clip from the box and pigtail those two grounds to a 6" piece of bare copper wire. Install your bracket. Wrap your extended ground wire around the green screw on the bracket. Connect the end of the extended ground wire to the ground wire from the fixture with a small wire nut.