I bought the same awning from ARB. One of my first uninformed choices. It did not come with any mounting hardware. I called them directly they said.. "just go to Lowes and buy some bolts it's pretty easy to do" (that's a quote as I still have Thier pithy little email. They ended up sending me some L brackets after a couple more emails. I've been moving that awning from house to house as other things took priority with my rig. Getting back to the awning today, trying to find the right size for the T slot . this post saved me lots of time.
I despise arb.. Their gear is gaudy, over priced, incredibly heavy and marketed to the masses. I'll use the awning as it's paid for but black out the label. I'd rather not have the gear of arb are the only ones who sell it.