For this course, we've updated the project files to Unity version 2020.3 (LTS). This is a long-term support version, which is recommended by Unity. LTS versions get released each year and are stable foundation for you to build your projects from.
First, open up your Unity Hub and navigate over to the Installs screen. Then, click on the blue Add button.
This will open up a smaller window with a list of Unity versions. Under the Recommended Release header, we want to select Unity 2020.3 (LTS). From here, click Next and follow the install process.