I’ve done this on my fabricated garage.
The reinforcement bars are in the thick edge pieces, and a drill has huge problems getting through. The thin part of the panels dont have reinforcement and drilling here makes bits of the panel burst away.....they are very hard concrete. It is possible however with an SDS drill at slow speed.
I have had reasonable success by drilling through where the panels join, and passing a bolt through with a large washer on the outside.
I’ve also used the bolts that connect the panels together to help, sometimes using longer ones.
Be lucky.....what should be quite simple is unfortunately more awkward that it seems!
John