To generate Google Maps API key that can be used for Composer Online Customisable Maps please follow next steps:

1. Follow the link: Google Maps Platform - Location and Mapping Solutions 

2. Press a Get started and move to the next screen.

Once read Terms of Service, tick the corresponding checkbox. Subscribing to the email updates is optional.

3. Identify Verification and Contact Information. Enter the mobile phone and a verification code to confirm the identity and location.

4. Fill in payment information to pass a verification.
   4.1 Choose your account type:
   - Business;
   - Individual.
   4.2 Fill the Tax information: tax number, VAT registration status and phone number (the required info depends on the location country).
   4.3. Name and address
   4.4 Payment method (a required field).

5. Once all the info is filled, press Start my free trial. After this, a Google questionnaire will be available (and be unskippable).
   You will be asked to share:
   - primary goal of signing up for Google Maps Platform;
   - industry the user is involved in;
   - use cases that the most fit the needs;
   - company size.

6. After this, the API key is available in the popup window, feel free to copy it.
   Selecting the checkbox Enable all Google Maps APIs for this project allows to call any Google Maps APIs from this key. Enabling an API does not have a cost, and it is possible to restrict using the key from the Credentials page at any time.We recommend to save this setting to prevent any additional settings of disabled APIs.
   Selecting the checkbox Create budget alerts allows to be informed about an unexpected bills. This setting can be changed in the Billing section at any time. We recommend to save this setting.

The API key can be found and copied on the Credentials tab on the Google Maps Platform as well

7. After going to Google Maps platform, Google will offer the user to protect the API key via several options (optional):

8. The next step, the Overview page of Google Maps Platform will be available. To find the API key, follow APIs tab in the left sidebar:

9. On this page, there are all enabled APIs collected. Be sure, there are the must four APIs available:
   - Geocoding API
   - Geolocation API
   - Maps JavaScript API
   - Places API

10. After clicking on any of them, its settings are available to be managed. The option to disable the API shows us that the current status of a particular API is enabled.

11. In the Credentials tab, there are all credentials compatible with this API are available. It is possible to create another key and configure OAuth consent via this menu:

12. Copy the API key and paste it to the relevant field in the Org Settings -> Google APIs tab at the ComposerOnline. Then, press Validate. In case the key is valid, it will display a successful notification and be saved. In case the key is not valid, the corresponding notification will be displayed, and the system will ask to check the key relevance.