Is there any way that you can temporarily disable the 5GHz network? (presuming you have both bands with the same SSID, right? - that’s why you can’t differentiate them during setup?)
Your iPhone should be connected to the 2.4GHz network that you want the ANova to connect to.
If you can temporarily disable the 5GHz band, then complete the ANova setup, you can re-enable it after the fact.