Mask help

Hello, I've just stepped away from Lightroom classic as I want to control my finances a bit better and I only tend to shoot photos in the warmer months so it never made sense to pay a subscription all year. I'm trying my best to get my head around the dark table interface but I'm particularly struggling at masks. To put some context I mainly shoot car photography and one of the key things I like to do is add a little bit of exposure to the wheels to make them pop a bit. When I'm trying this in dark table I can't figure out how to make it edit strictly what's inside the elliptic masks I've created. I group the masks together and when I edit one of two things happens, I can manipulate the wheels themselves but notice the rest of the image gets darker or vice versa. I'm struggling to strictly edit inside the masks without affecting the rest of the image.

A further question and one I have seen be asked beforehand. Is there a straight forward way to convert presets I made on Lightroom over to dark table? I fully understand it's not a straight conversion as the two programs edit differently however I've already removed Lightroom from my pc so I can't attempt to recreate the presets by direct comparison. Any advice and guides is much appreciated as I've found this to be a difficult transition . Thanks