M6 Pro NI MR65 Event setup

 Hi, all!

 I just Purchased a M6 PRO MR65 to provide wifi for an event taking place in an old building with poor cell reception. I'm purchasing external antennas to improve reception for the hotspot, and looking at the AC1200 WiFi Range Extender (EX6120) range extender. I read that you connect the extender to a router via ethernet cable, then use a browser connected to that router's wifi to set up the extender. Do I have that process right, and will this work with the M6 pro hotspot? The hotspot does have a Gigabit ethernet port. Seems like it should work, but wanted the opinion of others before ordering. Thanks!