Setup learning environment failed: Configuration dbacademy.library.version is not available.

NSJ
New Contributor II

Using 1.3 Getting Started with the Databricks Platform Lab.  to self learning. When I run DE 2.1 to setup environment, got following error:
Configuration dbacademy.library.version is not available.
Following is the code in the common setup.

specified_version = f"v3.0.70"
key = "dbacademy.library.version"
version = spark.conf.get(key, specified_version)

Which version should I use?