There are two likely causes!
The most common issue is not including the Monto global header script on your site. To check this, please:
Log into Monto
Navigate to the app that you have activated (trial or on a paid plan)
Go to the Setup item under that app
Check to see if "Global header script is detected"
If it is not detected, then you will see instructions detailing how to insert the script to your shop or site
Other potential issues to watch out for include inserting the Monto header script twice (this can cause our app to not perform correctly) and also inserting the wrong script. That can happen when you have a separate development environment than your live site, or if you moved your Webflow site from one account to another.
Sometimes people can also have multiple Webflow projects that look similar (or are even named the exact same thing) and they connect the wrong one by accident. So be sure to double check that the script included in your Setup instructions in Monto matches what you have inserted on your site!
If that happens, please watch this video detailing how to change which Webflow project you have connected to your Monto account: