Plugin

When i tried to install F3X Import and ThreeDText 2 Plugin, i always get the "Unable to Create Plugin File"

How to fix it on Mac?

Does getting a plugin automatically installs it? and if there is nothing in roblox plugin folder am I save?

So, I've been trying to scale UI elements in my game to fit all UI on all devices properly. However, it just sends the stuff all over the screen on different devices, like nothing has changed. I thought of getting AutoScale Plus. It has a few more features that can help me but I'm not sure on whether I should buy it or not. Thoughts?