That's not really a good understanding - it may seem pedantic, but legal theorists and sociologists have very little to say about the 'real biological basis' of race; it's simply not within their purview. However, it may be used as an assumption or presupposition or not considered at all.

You mentioned 'and that the laws and attitudes surrounding race are primarily informed by this social construction' which correctly describes CRT, but it doesn't have anything to do with the biology (or lack thereof) of race.