This message occurs when User Management has been enabled but Conga has not been enabled for the user's login (the user is not listed as an authorized user in User Management).
The same error message can also result if the &DC (disable Conga) parameter is included in the Conga custom button/link URL but the &DCL (disable Conga label) parameter has not been included. &DCL provides a custom message when Conga has been conditionally disabled using &DC. If &DCL is not included, the default message is:
"Access not authorized. Please contact your Salesforce administrator and ask to have your name added to Conga Setup > User Management."
What to Do
To correct the error, go to Salesforce Setup > Installed Packages and then clickManage Licensesnext to the Conga Composer package and ensure the user has been assigned a license.
To learn about the User Management tab, see User Management Settings
If the &DC (disable Conga) parameter is included in the Conga custom button/link URL but the &DCL (disable Conga label) parameter has not been included, check the Conga button URL to evaluate the &DCL conditions and change as necessary.
