It is not mandatory to make a URL clickable, but if your report is an electronic document it is recommended as a service to the reader.
In applications such as Word and PowerPoint, links are automatically underlined and in a blue font, and in most cases they turn purple after they have been clicked on once. If you do not like this, you can remove the links' underline and/or change the colour. Consider what is most clear or organised for the reader. Make sure that the entire reference list is formatted in the same way (underlined yes or no, live links, same colour).
However, always present a URL as a hyperlink, beginning with http: or https:.