Since the latest update, Google Maps no longer supports access to their API without a key, because they are introducing paid plans. You would need to get one for your website in order to make Ventcamp maps to work. The good news is that there are still free plan to use them which is the Standard plan.
Choose or create a new project
Click "Create/Enable API"
Copy the API key
Paste it into Ventcamp API Integration page and hit Save!