Can't connect to CoxWiFi on OSX

I am sitting in a cafe with my Macbook open and trying to connect to a "CoxWiFi" hotspot.

When I do this, the wi-fi icon in the menu bar turns white, telling me I've got a great connection - but I get absolutely no internet. And no popup asking for my Cox customer information.

The official support documentation gives me no help. Is there anything I can do to make the login popup come up?

I'm running OSX Mojave, 10.14.5.