Apache not working with user Sites folder on macOS 10.13 High Sierra
This worked for me when I ran into the same problem.

Please check "/private/etc/apache2/extra/httpd-userdir.conf" file.

change

#Include /private/etc/apache2/users/*.conf


to

Include /private/etc/apache2/users/*.conf


and restart apache.

From: https://stackoverflow.com/questions/39631351/apache-localhost-403-forbidden-with-macos-sierra