My solution would look like this:
My reason for the above answer
The amino Group is more activating than the nitro group and therefore the diazonium salt had to be on the left ring.
Is this correct? If not, what is the correct explanation?
Edit: To get to the azo-coupling product shown above I should use a high temperature, or? So, the reaction has to be thermodynamically controlled because the azo-group is localized on the 𝛽 carbon.