Ok, so this is a common problem with Free Edition. Since DBFS root is disabled on Free Edition to use Autloader you need to use Volumes. So all your source file that you want to load along with autloader schema and checkpoint location should be defined on Volume.

You can follow below guide which deals with exact same issue as yours. Just replay the same steps as the author of the article and it will work 😉

When DBFS Is Not an Option: How Databricks Volumes Saved the Day for File-Based Learning on Free Edi...