I feel your pain. Welcome to Manjaro Linux.
Middle click copy/paste is a (cancerous) default setting in X11/Xorg Server. There is no option to disable this setting however there is an option to make the middle click behave like a scrollwheel where you can move the mouse up and down to scroll (not like on windows tho), the catch with that one is however that it completely overrides all middle mouse clicks, e.g. u can no longer use middle mouse clicks to for example click on links to open them in a new tab, or in games.
You are in luck however, if you are on AMD hardware as your profile suggests, you have the option of just using Wayland instead which does not have this middle click pasting option enabled by default (although some desktop environments for wayland, like say KDE, might have this option enabled by default, you should at least be able to disable it)
There are two ways I know of to get rid of middle click paste on X.
1: Install this package and autostart it on every boot.
Downside is that if you copy text from an application, then close that application, your copied text will be forgotten by your clipboard, you can use your clipboard manager to get it back though but it is annoying.
2: Follow the steps in this particular answer:
Downsides are the same.
As for the autoscrolling (which is what the middle click to scroll function available on windows is called)
Autoscrolling is actually not enabled by default in windows, it’s a feature of windows but applications have to specifically support it, and most applications do not support it, some key ones however (like say web browsers) do.
There is no autoscrolling support specific to linux, that does not mean you cannot get autoscrolling on linux.
First you gotta ask yourself where you actually need autoscrolling, if you just need autoscrolling in your web browser that’s easy.
Assuming you’re using chrome/chromium there is a browser extension you can get that will enable autoscrolling for you like you are used to on windows.
If you’re using firefox, it’s simply a setting in firefox that you have to enable to get it.
If you want system-wide autoscrolling (something that windows does not actually have as I mentioned before) there has been some discussion and attempts at that here:
If you want to use that script, be careful to use Cestarian’s latest script rather than Azerothian’s which is slightly outdated.
This method only works on X Server and not on Wayland.