Is it Difficult to use professional DSLR cameras as a beginner?
Difficult?.. no.. as long as you understand how to use the camera and can take advantage of its technical features.
Most Canon, Nikon and Sony DSLRs like the 5d mark 4 are very easy if you set up everything to “auto” mode..As you use more, you will educate yourself on the functions of the shutter, aperture and ISO in making exposures. This is the minimum you must do if you are to be in control of your photography/cinematography. Dont rely on auto-expousure unless lightning conditions make manual adjustments impractical.
Also, educate yourself on the cameras many other useful functions(way too many to mention here). Get to know the camera, and it will be a great tool for you.
Having said that the setup is very expensive but if your budget can handle it go ahead.