Learning new role

What is the best way to attempt to learn a new role? I am trying to learn ADC, and I am really struggling.

My biggest frustration is that I keep getting paired against laners with much more skill and it really makes it not fun at all. For example, my last game the laner was a plat 3 ADC main. I'm gold 5, and that is based off of my main role (jg).

I know it is frustrating for my teammates as well for me to keep getting stomped, but I really want to learn a new role. I remember there used to be team builder that said that it scaled your MMR if you were in a new role. Is there any other way to learn a new role without getting stomped by players with much, much better skill than myself? It's hard to even learn basic mechanics when you can't even farm or do anything because you're dying under turret.