It turns out this was fairly simple:

Navigate to https://www.microsoft.com/en-us/sql-server/sql-server-downloads
Download the SQL Server 2017 Express
Install SQL Server
At the end of the installation, click on the Install SSMS button
When that is done, close both windows.
Restart computer
Navigate to https://github.com/Microsoft/sql-server-samples/releases/tag/adventureworks
Download AdventureWorksLT.bak and save in C:\Program Files\Microsoft SQL Server\MSSQL14.SQLEXPRESS\MSSQL\Backup
Launch SQL Server Management Studio (SSMS)
Right-Click the Databases node
Choose Restore Database
Under Source choose Device and click the browse button at the right
Click the Add button
Navigate to the BAK file you downloaded (should be the path noted above)
Click OK
Click OK
Click OK on restored successfully message
Expand the Databases node and you should see AdventureWorksLT in the list of databases.