AWS: S3 Bucket AWS You can't grant public access because Block public access settings are turned on for this account
It seems like it has to be unchecked from both places Permissions and Block public access (account settings).
I hope you have sorted this out already, if not go to Edit public access settings
then type confirm in the next screen to go ahead with the change
In addition to walterc's answer, if anyone is still having problems I had to click into the specific file I wanted access to and click "Make Public" for that file as well since just Making the bucket public won't work for specific file link access.