To setup the Mockup URL Make sure you have the Active site you are trying to edit set as active. You can view this here:

1. Click the gear icon > Click "Domains" > Click "Add Subdomain"

2. Add M# + Account Name as the subdomain and press save 

3. Select "Set as Primary" and press "Activate Domains"

4. Refresh and verify your URL has resolved

5. Press "Publish"

6. SAVE SUBDOMAIN YOU SETUP IN TODO COMMENTS / CRM in the use case above it would be: