In this way, wholeheartedly embody the endlessness and roam where there is no sign, fully realize whatever is received from Heaven, but without thinking anything has been gained thereby. It is just being empty, nothing more.
"Fully realize whatever is received from Heaven." How could we wish to do anything other than this? Well, not everything we have received pleases us; life comes with death; the full bloom of youth ends in sickness and decay; the 'me' experience likely becomes no experience at all. The human experience comes in a particular package and the happiest way to experience it is to fully embrace it all; whatever is received.
Yet, here Zhuangzi is probably speaking more to the sunnier side of life; fully realize your humanity. Make the most of it. Enjoy it to the max. The hard parts only help us to do just that. Never are we required to negate anything that we have received. Is there anything we have not received? Daoism is life-affirming. Grow, prosper, fully live out your days. Enjoy. This very life is all that need concern you; from whence it came and to where it goes, these will take care of themselves. You need not "work out your own salvation with fear and trembling" because there is nothing that needs saving. All is well. It's all taken care of. Trust to the goodness of what is; it will be what it is in any event.
"Heaven", of course, is not an intentional thing; it is not a deity. Heaven is this happening, this cosmic event of which we are a part. Heaven is Nature, things as they manifest. Heaven is Mystery, for things are thus and we have no understanding of a why or wherefore.
The question remains if we have received something of which we are unaware. Is this a call to realize some essential "true" self that lies beyond our actual self in its interface with the life experience? I think Zhuangzi implies no such thing. I believe he calls us to fully realize this life that is experienced, not one that is not. And this calls for an engagement that is embracing and affirming of that experience, one that does not negate and flee it for some hypothetical other. Drift and doubt, our tenuous existential presence, are not subsumed by some imagined resolution but are the very vehicles upon which we mount and transcend into freedom, the freedom of abandonment and thankfulness.
You can check out Scott's writings on Zhuangzi here.