There is a rope sewn into the seam of the awning that is supposed to slide into the slot in the awning rail. The instructions for installing the awning fabric call for using a tool to "slightly spread the ends of the awning rail" so the fabric can be slid into the slot easier. Then, the instructions call for squeezing the awning rail closed and after making sure everything is working, to install a small screw into the awning rail, through the rope/fabric to keep it from moving.
It looks like whomever installed your awning may have "skipped a couple of steps"........
You can push the rope/fabric back into the slot, use pliers to squeeze the slot closed (not too tightly, use the other end as a measure) and then install the same type screw in that end as is installed in the "other end".
While you don't need all the instructions, here is the instruction set for awning fabric replacement. Read through them and you'll get an idea of the steps above complete with pictures. It's a simple task, no need to go back to the dealer, but if you don't feel that you can do it, there's no shame in asking the dealer to fix it.
https://www.e-carefree.com/documenta...n%20Manual.pdf Spreading the awning rail slot is on page 4 and securing the fabric is located on page 9.