[keycloak-user] Share resource with Direct Access Grants Enabled OFF

i've read the documentation, this point in detail https://www.keycloak.org/docs/latest/authorization_services/index.html#ot... If i set Direct Access Grants Enabled to ON, i can get the access token and i can use this token to SHARE the resource, tried this with postman and everything goes well, but if i set the Direct Access Grants Enabled to OFF, i cant get the token to authorize the share request. What i'm missing ? How i can get the token to authorize the share request? What part of documentation i need to check? Thanks in advance, for any help. Nicola