Can't attach Orbi Satellite

Netgear recommends fewer than six satellites on this model:

https://kb.netgear.com/000062035/How-many-satellites-can-you-add-to-an-Orbi-WiFi-System

However, Netgear does not say it is impossible to connect six satellites. (only that they do not recommend doing so)

On the original Orbi WiFi5 products, a common practice was to temporarily power off existing satellites while connecting a new one.  It might be worth trying powering off the satellites that would not be required to get this sixth satellite connected.  (i.e. if the goal is to "Daisy Chain" this new one through an existing satellite, then it obviously has to be powered up. But satellites "on the other side" of the network would not be.)