If you want to read from your Azure storage account using Databricks Free Edition, you can add a specific option when reading:

spark.read.option("fs.azure.account.key.<storage-account-name>.dfs.core.windows.net",
                  "your_storage_account_key")

I just tried and it worked 🙂   However, I could not achieve the same with dbutils.fs.ls("abfss://....") which works well in Azure Databricks, but I cannot find where I can pass the same option.