We recommend first to mount the woofers onto the baffles, and then mount to baffles with the woofers onto the frame.
To mount the woofers onto the baffles use 8 x M6 bolts and serrated nuts
You can put the baffle on your knees or between two chairs, and place the woofers (starting with two bolts), so their posts for the cables will point to ~5PM when looking at the baffle from the front.
One by one, insert the other 6 M6 bolts and tighten all of them relatively strong, but not to a level that the ring might deform.
Once both woofers are mounted, you can mount the baffles with the woofers onto the frame.