The sample databases for SQL Server are all documented here. They point to the Github repo where the actual DBs reside.
As discussed there the AdventureWorks DB is an older example and MS has moved on to Northwind. However you can still restore the older DB into a newer SQL version. There hasn't been any changes since 2012. The SQL DB and data warehouse DBS are stored under the releases here. Grab the version for SQL2016.