"We now have everything in our own hands. We said that we really liked him and they offered to assist, but we do it on our own," technical manager Ron Jans told De Telegraaf on Wednesday.
"The connection with City is positive."
On Doan, Jans added: "It's incredibly good to be able to adapt so quickly at such a young age in a completely different culture.
"A big compliment to that boy."