I did basically what David suggested. I redrew your model but I made a few modifications.
First, I dragged out the radius of the circle on axis instead in some random direction as you had done. Dragging out on axis makes it easier to work with the circle. I also started on the origin because that makes it easy to find a center point for the resulting radial array on the bottom. I set the number of sides on the circle to a value divisible by 5 since your model shows 5 notches. This makes it easier to ensure intersections where the straight line segments of the U-shaped notches meet the edges.
Next, I use Push/Pull to extrude the U-shaped faces up through the top. I hit Ctrl to allow the tool to extrude beyond the beveled top surface.
Intersect Faces made the intersections between the vertical faces and the top surfaces of the disk.
Finally, delete what isn’t needed, correct the face orientation in the notches and soften edges.