将一个组件垂直居中,并将appbar置于屏幕材质UI的顶部

I am new to material UI, and am having problems centering a component (horizontally and vertically) whilst including an AppBar for navigation at the top my screen. I understand that there are solutions like this, using a grid, however, this will align ALL items, including my AppBar in the middle, which I do not want. Any help would be greatly appreciated, as I have been pulling out my hair trying to work this out (I'm usually a backend dev).