The pre-collapse star is spinning for the same reason: any nonzero angular momentum in the very extended gas/dust cloud from which it formed gets concentrated a

The pre-collapse star is spinning for the same reason: any nonzero angular momentum in the very extended gas/dust cloud from which it formed gets concentrated as it collapses into the star. In fact, there's typically so much angular momentum it can't go into the star, but instead either goes into more than one star, or into a pre-planetary disk around the star.