The WN3000RP is a wireless extender, as such there is no direct App support.
If however the WN3000RP is linked (as an extender) or wired (as a wireless access point) to a router supported by the Genie App, the Network map will show the WN3000RP, and you can click in the map on the extender to see the associated and connected devices.
Any apps for a device will show up in the Firmware and Software Downloads section of the support pages for your hardware:
There is support for this device at the end of this link:
>>>> WN3000RPv2 | Product | Support | NETGEAR <<<<
If there is nothing there, then, as @schumaku says, there are no apps.
Just another user.My network DM200 -> R7800 -> GS316 -> PL1000 -> Orbi RBR40 -> Orbi RBS50Y -> RBS40V