Have a look here: https://www.youtube.com/watch?v=iSbmB7ZJ5zw

Basically, I had to change the URI's from http to https.

Instead of: tomcat-users version="1.0" xmlns="http://tomcat.apache.org/xml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://tomcat.apache.org tomcat-users.xsd"

This one worked: tomcat-users version="1.0" xmlns="https://tomcat.apache.org/xml" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://tomcat.apache.org tomcat-users.xsd"