You are trying to add a hyperlink for your calendar event token to text in an email, but when you click on the link in a sent email, you are not getting an ICS file.
When you add the calendar token to an email, it displays as a "My token." Once the email is generated, that token will then appear as a link in your email. However, if you try to hyperlink the token, the token cannot resolve.
To get the calendar file token to work properly, you need to add the token to the email by following the steps in this document: Include a Calendar Event in an Email. Note that you should add the token using the Insert Token button, rather than the Insert/Edit link button.