Getting 403 Error Pointing Custom Domain to Github Pages Site

Hi all. I made a GH pages website a long time ago but never finished it. I finally decided to purchase a custom domain and point my domain back to my page. I currently have the A records for the Github IPs as well as a CNAME alias to my Github page set on my domain and a CNAME file pointing to my domain on my site. However, whenever I try to access the site I now get an error saying “Forbidden. You do not have permission to access / on this server.”

I have never tried to alias a site to another site before, and as far as I know I haven’t had to do any server config work with my Github page to fix this. Can somebody help point me in the right direction?