I suspect that I, a mere human, am more confused than Jesus.
But this clearly refers to Mary of Magdala, not the Virgin Mary. And the NAB says that:
“Stop holding on to me: see Matthew 28:9, where the women take hold of his feet. I have not yet ascended: for John and many of the New Testament writers, the ascension in the theological sense of going to the Father to be glorified took place with the resurrection as one action. This scene in John dramatizes such an understanding, for by Easter night Jesus is glorified and can give the Spirit. Therefore his ascension takes place immediately after he has talked to Mary. In such a view, the ascension after forty days described in Acts 1:1-11 would be simply a termination of earthly appearances or, perhaps better, an introduction to the conferral of the Spirit upon the early church, modeled on Elisha’s being able to have a (double) share in the spirit of Elijah if he saw him being taken up (same verb as ascending) into heaven (2 Kings 2:9-12). To my Father and your Father, to my God and your God: this echoes Ruth 1:16: “Your people shall be my people, and your God my God.” The Father of Jesus will now become the Father of the disciples because, once ascended, Jesus can give them the Spirit that comes from the Father and they can be reborn as God’s children (John 3:5). That is why he calls them my brothers.”
So again we have the dual nature of Jesus illustrated.