You don’t need to receive another file, you just need to ask the person who controls access to check if you have the correct permissions, if the environment variable is correctly set up, and verify this once all is done. You can check more in Getting started with authentication and Authenticating with a service account key file.
However, there is the possibility that this message is caused by other means. First, check you have all the required permissions. Verify you are not using public datasets, or similar stuff that might need some extra steps. If the service account is correctly set up, you can try creating a new one, as seen in that question, although in this case you might need to update the json key. And finally, check you are using the correct type of permission.
You can check all the permissions in the Understanding Roles documentation.