Please refer the below document to generate API Key.
1. Go to the OpManager Installation folder.2. Open map.html from <OpManager_home>\apiclient\fluidicv2 directory.3. Append the API key in the Google map URL as a parameter like (&key=<Your_API_Key>), In the script tag's src attribute.Example:If your API key is xxxxxxxxxxxxxxxx. The script tag will be.<script type="text/javascript" src="//maps.googleapis.com/maps/api/js?sensor=false&language=en&key=xxxxxxxxxxxxxxxx"></script>4. Save the map.html file.5. Wait for 5 mins to API Key reflect in Opmanager.