Given that the screen will only stop rather large pieces of debris, the reality is at that point you recognize its catching stuff,
you have bigger problems to be concerned with.
My belief is the screen is a hold over from the T1 design w/o a spin on filter.
So no its not necessary.
But.. if you want you use it, its not that hard.
1st - you need a third sealing ring to sandwich the screen flange between the sump mating surface & the cover.
2nd - you need to ream the hole in the thin alum. on the bottom of the screen that is only as large as the M6(?) sump stud, to a hole that will fit the female securing stud .. snugly. Go slow & work up to your fit. If you just hit it with a drill bit you may not like the results BTDT.
Last - I also used a file & opened up the slots on the base to allow a bit more flow, no real evidence that it is necessary it just made me feel better.