Does anyone know if you can install a Flood Light camera to a non-circular, more rectangular junction box?
Glad you asked @Eldurso! The Floodlight Cam should be installed on a 4 inch, waterproof, round junction box for optimal performance and intended positioning. Check out our help center article about mounting the Floodlight Cam for more details 
What are your options if your existing light box is not round? I have a hexagon shape so I can’t use any of the mounts that came with the spotlight camera mounted.
Hi there, @kt1977! For the Spotlight Cameras, some models (Spotlight Camera Mount) will allow mounting to a junction box. Check out our help center article for installation tips and a video showing the mounting options.
For any Ring devices that feature wiring or use of a junction box, we advise consulting with a licensed electrician for installation. As it sounds like the junction box might need alteration to fit, an electrician should be able to help there as well.