Our window awning kit from A&E came complete with all hardware including the expanding pop rivits mentioned, screws, etc. I installed using the pop rivets and all went surprisingly smooth.
I was more comfortable using pop rivits vs. screws because we have a 9 year old coach and I was concerned that the old thin fiberglass might crack from the screws.
I cut butyl rubber pieces to go under each attached support, and then finished with caulking.
One nice thing, our MH already had awning channels down the full length of both sides, so I just slid the window awnings into place in the existing channels. No need to install the ones with the kit.
Since you've already ordered yours, this comment may be a little late...
We bought awnings on clearance, so we had limited choices for size and color. Found some which matched our patio awning, but were much wider than the window -- 54" awnings, 37" windows. We thought "what the heck, we're saving hundreds of dollars". Well, I'm glad we have the wider ones, and if I had it to do all over again I'd have bought the 60" awnings! Two reasons; rain doesn't always fall straight down, and the sun isn't always straight overhead