Hello! I have the same problem and your solution doesn't work. I've tried both .databrickscfg and DATABRICKS_TOKEN, still this "No api token found" when trying to access an external table on Unity Catalog, or doing anything with Unity for that matters (for example "use catalog").

However, if I read directly the delta table (the table is mounted on the dbfs) then there is no error.

The problem seems to be located to Unity Catalog itself, the connexion to spark have no problem because I can work fine if I avoid using unity tables.

It's still a problem for me, because we're trying to remove the direct mount of the tables, to force the use of Unity Catalog to manage access right, and with this bug we can't.