I've had volunteer squash try to grow in unprepared clay soil and become stunted. Is your top soil a pretty good depth? The leaves on the plant look healthy but kind of light... So the plant may just need to be fed.. It don't know if it's just the picture though.

Plant gets plenty of sun and water. and it (and my garden) have had a couple miracle-gro liquidfeed feedings so far. I dunno if it got stunted some from a post last frost date chill or what!

It doesn't have Squash Vine Borers does it?

Squashes don't like being transplanted. Yours could eventually settle in and start to grow.

Only transplanting was from bonnie's pot to garden.

Give it time and water. It does not look that bad. Mine started to look like that and not grow very much and the Zuk's were small, found out my husband wasn't giving them enough water.