I have moved this topic to the appropriate forums for cloud flows.
As to your question, after you enable the HTML editor as suggested by @Deenuji , you can build a hyperlink in HTML as follows:
<a href="YourURL">Your Text</a>
This will make the hyperlink actually clickable and not just a plain text URL in the email body. And it will also be behind a text that you define, so the body will look nicer.