To use Mapbox tools and basemaps, you must sign up for an account. This is a straightforward process and involves supplying a username, an email, and a password:
Once you are signed up, you'll be taken to the Account Dashboard, where API access token can be generated and Mapbox Studio can be accessed. The Dashboard also has your account statistics on the number of API calls to the variety of services available, including directions, geocoding, and datasets.