I have the solution kindly given to me by Ruckus Personnel: Since the AP doesn't know ehich VLAN it has to use for management one has to configure this parameter manually on the AP interface. For example for ZF7363, on the GUI, first on "ethernet ports" you have to configure the port that it will connect to the network as "trunk". Then on "Internet" you look for the "management vlan" field and there you specify the ID you have previously configured on the ZD and voula! the AP integrates with the controller!