This activity applies to you only if either your computer does not have the Java JDK or jGrasp installed upon it, or if you wish to install more recent releases.
The page has four dropdown boxes in which you can make choices (in order to narrow the list of "products" presented to you on the web page). In addition to selecting the Operating System and Architecture consistent with your computer, you should choose "JDK" as the Package Type and "21 - LTS" as the Version. (If you need help in determining your computer's architecture, ask your instructor.)
If you want the freedom to place the downloaded files where you want and to configure your system to be able to use them, you can download the "archive" (.pkg file for macOS or .zip file for Windows). More likely, you will want to download an installer, which would be the .pkg file for macOS or the .msi file for Windows.
There are a variety of "integrated development environments" (IDEs) intended to provide support to a programmer. A simple one that we encourage students to use in the first couple of CMPS courses is jGrasp. If your computer doesn't already have it (e.g., from when you took CMPS 134), you are encouraged to install it. The link in the previous sentence goes to the jGRASP website. This link goes directly to the jGrasp "download" page.