In order to run your local environment, you'll typically want to be able to create and manage your own databases as well as a clone from production, UAT, etc. and make backups, create T-Sql scripts, etc. With that in mind, we'll walk through how to create your local SQL environment.
First, you can download the SQL Server "Developer's Edition" and this (at the time of this writing) doesn't have any licensing restrictions so long as it's used solely for development. You'll ideally download the same version as the SQL server that the marketing production environment is on (note that if you download a newer version it's fine, you'll just want to consider that a few things you do on your local may not end up being compatible with the slightly older version of SQL). In addition, if you plan to make a backup from your local and move it to an older version of SQL Server that will require scripting in order to migrate things to the older database version. Again, this is solvable, but you'll want to consider the cost-benefit.
With that said, as of this writing, here's a link to download the latest version of SQL Server developer's edition that includes the SSMS (SQL Server Management Studio) you'll also need.
https://www.microsoft.com/en-us/sql-server/sql-server-downloads
https://go.microsoft.com/fwlink/p/?linkid=2215158&clcid=0x409&culture=en-us&country=us
(Note that the Google search to find this page was "MS SQL server developer edition")
During the installation process, there are many steps where you can choose options that will provide various different levels of functionality. In general, you'll want to complete a fairly standard if not basically 100% default installation and simply make sure you note that the "mixed mode" authentication is recommended and that you document any user/password combination you create so you can recall it later.
Download SQL Server Management Studio (SSMS) - SQL Server...
Once you complete the installation, you can download SSMS here if it wasn't included:
(Note that the Google search to find this page was "download microsoft ssms")