Step 1

go to https://www.microsoft.com/en-in/sql-server/sql-server-downloads

download developer edition

Step 2

1. Run the exe

2. choose custom option

3. select New SQL Server stand-alone installation in the Installation tab.

4.select the free edition

5. install Database Engine Services

6. set instance name

7. set server configuration - startup type

8. set authentication mode - mixed mode