Eureka!
If your Macintosh has a T2 security chip which my 2018 Mac Mini does, then you're going to have to go to system preferences > security and privacy > privacy> full disk access. Then use your computer password to change the security settings by hitting the lock button to unlock it. Then hit the magnifying glass type in obs and select open. Then we like it. Restart obs. And Bam you allowed OBS to use Safari.
Just in case this happens, you should do it every time you either update OBS because permissions do not carry from one version of OBS to another as well as every new update of the operating system.
These are instructions for allowing OBS to display a Safari window. Maybe someone else could give details of allowing OBS to use a chrome window.