It is not really a Splunk question. The following Google search throws up a number of different sources of information. The top hit (in my results, at least) is for Google's own documentation for Maps at Work (i.e. the subscription service). I would imagine that they would have a similar page documenting the free service requirements.
I'd start by adding the URL to your white listing, so that any variations to /maps/... are accepted also
"https://www.google.com/maps/*" "googleapis.com/*" "gstatic.com/*"
Presumably your internet is restricted by a proxy firewall, therefore the admin just need to add that URL's to the rule set, to allow you to browse.
You also need to understand what other URL's are used by the app, so install something like scriptsafe, which should show if anything else is being requested.