When we had a manual awning we used a couple simple dog leash ground screws we had laying around:
I then used a rope, later a ratchet strap hooked over the roller at each end of the awning, coming down to the dog screw. Between the dog screw and the rope - or ratchet strap, I connected them together with a bungie cord for some "spring" action, so if the wind blew or rocked the trailer, there was still tension on the awning arm, but not much there was no give, potentially bending the awning arms.
We did this for years, until our current trailer that has an electric awning, which behaves much different now.
If you have these parts laying around, it's simple, effective, and works very well. You can try a different anchor in the ground, a tent stake, or something like that. We just happened to have 2 dog stake screws we weren't using and dedicated them for this purpose.