Scrolling is a hot topic for people who use MacBooks. Some people prefer natural scrolling on the trackpad. Natural scrolling means that when you drag two fingers upwards on the trackpad, your Mac will scroll down. When you drag your fingers downwards, it'll scroll up. It might sound counterintuitive, but it's similar to how you might move a piece of paper in real life.
Your Mac comes with natural scrolling on by default, which means that you'll scroll in the opposite direction of your fingers' movements. Some people prefer this type of scrolling, but if you're used to Windows, you might want to turn it off.
Then there are people like me, who like natural scrolling on trackpad, but prefer un-inverted scrolling when using a physical mouse (or vice versa). MacBooks only let you select one option for all inputs by default, so to enable this, you'll need Scroll Reverser, a free app that lets you set up different scrolling directions for your trackpad and your physical mouse.
Once you install the app, it'll ask for Accessibility permissions, which will let it monitor which device you're using and enable the right settings for you. Grant these permissions. Scroll Reverser will then appear in the menu bar. Select the app and go to Preferences. Next, check Enable Scroll Reverser and adjust your settings. I like to turn on both Reverse Vertical and Reverse Mouse. Before you finish, go to your Mac's System Settings, head over to the Trackpad section, and either enable or disable Natural Scrolling based on what you want your default to be. I like to leave it on.
With these options enabled, Scroll Reverser will do what you need it to—leave natural scrolling untouched on the trackpad while letting you use un-inverted scrolling with your mouse.
This app has one more feature that's useful for people who use a mouse with their Macs. You can configure the size of each "step" that the scroll wheel takes. Quite often, a single step in the wheel drags the page too far up or down, so it's convenient to be able to use Scroll Reverser to change that to your liking. To do this, go to Scroll Reverser's Preferences and move the slider below Step size. Increase or decrease this until you get your desired scrolling behavior.
Now that this is done, you can consider adding a nifty middle-click button to your Mac's trackpad and mouse.