Sometimes the Fire stick doesn’t like the logon screen for Hilton WiFi, and gives an error even when other devices are connecting fine. The way around this is to connect to another network (for example tethered to your phone) and open a webpage on the Silk browser. Then switch connections to the Hilton WiFi and then quickly go back to Silk and click on a link. This should open the WiFi login page in Silk and let you re-enter the details without hitting the error. Doing all that is easier said than done and normally takes a few goes.