There are two ways to include a link in your email.
Just include the link. Text that looks like a link, eg https://example.com will be automatically turned into a clickable link.
Or to make some text clickable use this syntax
[The text to display](https://example.com) which will result in this output: The text to display
Whenever an automated email is triggered (for example, you accept some submissions, which will trigger notification emails) you are you are presented with a screen to enable you to make any ‘one off’ changes required for that particular submitter.