Here is a complete solution that works really well: https://github.com/mcguffin/acf-field-openstreetmap
ACF Google maps field just lets you hook up a field to your Google API account. Now that it’s a paid service, you’ll need to add a payment account to your Google API account. It’s really not much to do with ACF, and not something they can “solve”.
Alternatively, use this field plugin to use OSM, a free alternative:
https://github.com/mcguffin/acf-field-openstreetmap
I am currently swapping all my sites over to use OSM as I can’t justify the Google costs.
Please see my note on this post: https://support.advancedcustomfields.com/forums/topic/google-map-not-displaying-on-wp-backend/
You need to add a billing account to your Google Console account.
I think OpenStreetMap is a better overall solution; I’m switching over to it on the front end of my sites, and will look to see what’s involved with switching to it in ACF as well. Perhaps a new field type to provide different options.
For reference: You can use Photon for the address lookup/autocomplete (https://photon.komoot.de/) and leaflet as the rendering engine (https://leafletjs.com/).
Google recently implemented new billing rules for Google Maps.
In order to display maps on a website, you need to not only have a correctly configured API key, but the account used at Google also needs a billing account set up with a card assigned for any billing.
This has been announced in a few places, and if you click through the links provided on the greyed out maps and/or look at the details in the console you’ll see more descriptive warnings/explanations.
See: https://cloud.google.com/maps-platform/user-guide/pricing-changes/
In summary: the free tier has gone. You get $200 credit. Any usage above that is billed, so you need to add a billing account/card.