The mechanism to associate an authentication method with access to specific secrets is by specifying a/an:

An Accessor is a non-sensitive identifier for a token, used for management like revocation, not for defining access rules to secrets.

A Token is a credential issued by Vault upon successful authentication, which then carries associated policies to authorize actions, but the token itself is not the mechanism for defining those associations.

Policies in Vault define the authorization rules, specifying which paths a user or machine can access and what operations (read, write, delete, list, sudo) they can perform. An authentication method, once validated, is associated with one or more policies to determine its privileges.

A Secret is the actual sensitive data stored in Vault; it is the resource being protected, not the mechanism for granting access.