If you want to add a link to a text in the campaign, follow these steps:
Select the text to which you want to add the link and click on the link icon:
The following window will appear where you can enter a URL or an email. If you want to add an email, choose the "E-mail" option in the drop-down menu "Link type". If you want to add a URL, choose the "URL" option in the drop-down menu "Link type":
While still selecting the text, apply the colour of your choice and that's it!