The 4 holes were made by you. I just copied your parts.
If I made this, I probably would've laid this out in 2D (rectangle and circles), then used Simple Extrude (with "Use Compound Profile") to make the two parts.
Select the 120mm rectangle, the 4 small 2mm circles and the 55mm radius circle, then extrude 7mm. This creates the box with all the needed holes already made.
Now select the 55 & 59mm circles and extrude 120mm. This creates the cylinder with a hole in it.
3D Add the two extrusions and "Fillet Edge".
If you want the cylinder/extrusion to be wider, change the radius of the 59mm ‘circle’ to 60mm. The 3D part should get larger and the fillet will update.
Maybe this YouTube movie will help; https://youtu.be/zHur3z_zCrI
Designer, Deluxe, (Professional, Expert, Basic), Platinum
Windows 10 Pro (1803), 64-bit