Sounds pretty complicated.
Not really.
Medicare part A is hospitals, B is doctors, D is drugs, G is gap.
Do the signups 3 months before turning 65.
If you’re under 65 and getting soc sec, you get signed up for A & B automatically*, then all you need to do is sign up for D and G.
*Medicare sends you the card for A & B.
After you are signed up for D and G you get those cards from the companies offering the plans.
G pays the 20% that Medicare doesn’t.