That's a pretty small plant. The roots aren't very deep. Afternoon wilting is a standard response to heat stress for squash, especially in such small plants. As long as the stems are still erect, the wilting isn't going to hurt the plant much. As the roots get deeper the wilting will subside. If you're getting regular afternoon wilting, you sure aren't overwatering. Give it more. Give it a good thorough soak and then, when it starts to wilt, presumably a few days later, do it again.
You don't say where you are, but if it's hot and dry, that won't help. Because the sides get heated as well as the soil on top, containers tend to dry out more quickly.
If the wilting is just on one stem or vine, it's not about water. Check for squash vine borers.