An access token can be used as a bearer token in authorization headers. This is especially useful for authenticating CI servers with Artifactory instead of using credentials, since you don't need to have a user defined in Artifactory if the group provided in -d "member-of-groups:<GROUP>" is configured in that Artifactory instance. As a result, there is no need to manage fictitious users for your different automation tools that need access to Artifactory.
For example, to use an access token as a bearer token to ping Artifactory you could use:
curl -H"Authorization: Bearer <TOKEN>" http://JFROG_PLATFORM_URL/router/api/v1/system/ping