Yes it will work ok connected to the Ultra hub if you need a wifi extender in your house.
The 5ghz wifi in it is the same as the Ultra hub, but the Fastlane makes a difference for extenders. Fastlane uses a dedicated wifi connection back to the ultra hub, so if you are connecting it back to the Ultra Hub wirelessly it performs better than cheaper wifi extenders which dont have a dedicated wifi radio for backhaul.
I've used the fastlane feature and it works pretty good.
You do pay a premium for this netgear model though and a cheaper one with fastlane is as good (you'll not likely see a difference if you have less than 10 wifi devices online at once). The EX7700 is also designed to mesh with other netgears for seamless roaming between wifi nodes which it doesn't sound like you'll have.
Unless you are on gigabit fibre, even an AC1200 or AC1700 extender is plenty so I think you should save your money and go for a cheaper model.
Personally, Im on gigabit fibre with an Ultra hub (wifi turned off as it is in a wiring cabinet) and use a TP-Link RE650. This is AC2600 (compared to the netgears AC2200), it covers my 4 bedroom house with 200-600Mbit everywhere and it is $80 cheaper (at PBTech). the RE650 is the best extender I've used - and i've tested lots. The only thing better is a proper mesh pack which is what im currently using- TP-Link X60 triple pack, the coverage is massive and I cant trip it up at all, even it with many devices and tv streams on it at once.
@MrMorm - Thanks for the feedback. I've been digging around and settled on the FX7700's little/older brother, the EX6200 as more cost-effective solution. Looked at the TP-Link RE650, but have so few power points (old house) that I can't spare really one, also they're all at floor level so hopefully having the extender up a little higher on a shelf (and plugged into an existing powerboard) will do the trick.
Thanks again, I'm always impressed at the level of feedback one can gain on forum sites !!