No additional required beyond standard VDP project authentication. Note that Two Way SSL is recommended for the ATM Locator API.
You can get test credentials for sandbox testing online in the Developer Dashboard for the project. Production credentials will be issued as part of the production on-boarding process. Contact email@example.com for more information or to begin production onboarding.
As one of the security protocols, Visa Developer sandbox secures its connections with clients by means of Two-Way SSL (Mutual Authentication) method. Refer to the link below to quickly learn about how to get credentials to start building with Two-Way SSL.
Visit the Two-way SSL Guide to learn more.