One question that I see pretty often is why subtasks don’t appear in your Project calendar. This is a completely understandable question (and, trust me, it’s an idea that we’ve thought about) so I thought I’d take a few minutes to give more background.
If you think about how a Project is set up, you’re either going to be looking at it as a List (or Board!) or as a Calendar. These two (three!) options are your viewing options, but they’re going to show you the exact same tasks. If you do want to see your subtasks in your Project view, you can definitely add them to the Project (https://asana.com/guide/help/tasks/fields#gl-multi-home), but they’ll appear in both the List/Board and Calendar views.
With that said, all tasks and subtasks will appear in your Team Calendar if you’re working in an Organization (or your Workspace Calendar, if you’re working in a Workspace). This is because tasks don’t have to be homed in a Project (although I’d strongly recommend that they are), but the do have to be homed in a Team (or Workspace).