The court has approved the polygyny application. What are the next steps up to the akad nikah?

The next step is arranging the marriage at the religious affairs office, with the court order as an additional document. Get a certified copy of the order, then apply for permission to marry at the relevant Islamic religious affairs office. Complete the identity documents, the wali's consent, the pre-marriage course certificate and the health screening required by the state. Set the date of the marriage contract (akad nikah) with an accredited marriage officer. In all this busyness, do not forget your existing wife: tell her the date of the akad and the rota arrangements afterwards. Also comply with any conditions in the order, because they continue to bind you after marriage. See conditions of the akad.