If you are pressing D and looking for the develop module then it's possible that you installed the wrong version. Yes, there are two different versions. Lightroom is the cloud version, and it doesn't have a develop module. Lightroom Classic is the name of the other version. It DOES have a develop module. It does not store images in the cloud but allows you to manage everything locally on your computer. Two different programs for two different types of users. If you signed up for the photography plan then you can go to the creative cloud application manager and find that Lightroom Classic is also available for you to download.
Please note that while it is not called "Develop" in Lightroom, Lightroom does have (almost) all the same editing capabilities that Lightroom Classic has. They are all available in the Edit section (which, judging by the screenshot you provide, you have discovered). Some controls are hidden by default - click on the turndown triangles to expose the additional controls.