I gave up on the strap. I now use 3 or 4 of these on each side.
Drop ceiling clamps.I clamp them onto the awning then slip a 8" bungee ball loop through the end of the handle, loop it around the awning arm and slip the ball through the bungee loop.
With diligent shopping you can get the clamps in the 10 for $10 range. Bungee balls in the 25¢ range when buying in larger quantities. I always find other uses for extras.