It means you need to add the Google Maps API as starting June 22 this is mandatory.
This is a copy from Google Maps official announcement: As of June 22, 2016 we are making the following changes to the Google Maps APIs Standard Plan: We no longer support keyless access (any request that doesn’t include an API key). Future product updates are only available for requests made with an API key. API keys allow us to contact developers when required and help us identify misbehaving implementations.
Please see the video tutorial for all the details.