I tried to run the code (which was literally given to me by a 5-star company with good reviews whom I paid to write code for me) but the errors down below occurred:
The errors are telling you exactly what the issue is - you need to enable at least one plugin format through either the Projucer or CMake depending on how your project is setup.
But how do you do that? The company that programmed this software for me should have already done that. With all due respect, it still makes 0 sense.
I think this is something to take up with your developer 
But here is the official tutorial for the Projucer: JUCE: Tutorial: Projucer Part 1: Getting started with the Projucer
There you can enable the build for your required plugin formats. When you save Projucer and re-open Xcode, you should be able to build normally (if the original author used Projucer properly to create and setup the project).
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Well, as Rincewind says, that’s probably something you should discuss with them. We don’t know anything about your project or what they’ve provided you with beyond the screenshot you posted and all that tells us is that you haven’t defined some of the required macros that are usually set for you through the Projcuer or CMake.