The test email you can send to yourself to view a sample of the welcome email does not include a clickable Call to Action button. The Call to Action will appear as text for the test email and is done so in case the welcome email accidentally gets forwarded on.
The Nurture Cycle welcome email that gets sent to a contact when they are activated in the Nurture Cycle, will include your customized Call to Action and is dependant on whether they have completed their Value Builder Score or not. If they have not yet completed their Score, there will be a clickable Get Your Value Builder Score Now button.
If you would like to view the welcome email with the clickable CTA button visible, we suggest activating a test contact on Nurture Cycle.