Gateway Wifi Setup Without App

The gateway Wifi box came in the mail to replace my old router. The only instructions say to download the app. My phone is old and is not compatible. From browsing other questions I see I'm not the only one with this issue. Xfinity should provide a website for people who don't have access to their app. I've tried multiple things but every site eventually tells me to download the app... I don't know what to do next. Please help, is there a number I should call?