Don't let your fear prevent you from asking questions. Other engineers will be very happy to spend literal hours with you, including breaking down the overall

Don't let your fear prevent you from asking questions. Other engineers will be very happy to spend literal hours with you, including breaking down the overall architecture and figure out ways to contribute. Anything to help you get less lost in the sauce. Maybe carve out additional time to understand the project. The problems it solves may well be far beyond anything you've encountered. Thus the motivation for the project and the technical challenges it takes on en route to solving the overall challenge may all be opaque to you. Maybe toy projects and demos can help you build intuition for what's happening. Pay attention to the feelings of shame. You've done nothing wrong and this is a common situation. There are pros and cons to it. If you still hate it in a year you can take your new shiny resume and go find another job.