Your question is a bit vague. Which RingCentral product are you asking this particular question about? It should make no difference with regard to RingCentral as long as you have good internet access. I have a WiFi extender in my residence which I connect to when I use my laptop in certain portions of the house. I can reach the internet so I can use the RingCentral Admin portal, I can use the Windows application, I can use the mobile app, and I can use Glip without any issues.
All the WiFi extender does is EXTEND your network capabilities in or around a structure. It has nothing to do specifically regarding RIngCentral products other than you need internet access to use RIngCentral products.
I just installed a Netgear EX6400 and had it working successfully. RingCentral immediately stopped working. As soon as I unplugged the Netgear EX6400 RingCentral started working again. Was using the RingCentral app on my iphone 11