In that sentence, I would use the article. (I can't actually think of any situation where it would be used as a mass noun.)
However, if it were me, I would actually rephrase the sentence and turn real world into an adjective:
Build three high-quality real-world computer applications.
This sentence is not talking about money in general. It is talking about a specific set: "all the money in the world", as if it was a specific quantity you could receive:
Suppose I gave you a box with all the money in the world. How would you choose to distribute it?
Other examples talking about a specific set of money:
Do you still have the money I gave you for your birthday?
The money donated to charities should be included on your tax forms, if you want to take the deduction.
It is possible to talk about money as a concept, in which case you would not use the definite article. Examples of this:
I don't care too much for money, and money can't buy me love -- John Lennon / Paul McCartney
A wise person should have money in their head, but not in their heart. --Jonathan Swift
Money is a terrible master but an excellent servant. --P.T. Barnum
It is possible to say "all money in the world" to reference the global concept of money, rather than a specific quantity.
All money in the world, in whatever form, relies on the collective agreement that it is worth something. Even a brick of gold has no value to a starving man, unless he can exchange it for food.
[Edit] With regard to FumbleFinger's objection: I would claim "money donated to charities" is either a kind of ellipsis, or else refers to a conceptual subset of the concept of money. In my example, it makes little difference whether I'm talking in general about the practice of donating money, or of a specific instance of some quantity donated. The second half of the sentence applies either way.
Conceptual example: Money (which has been generally) donated to charities should be declared.
Ellipsis example: (The specific quantity of) Money (which you have) donated to charities should be declared.
I think a more in-depth exploration is out of the scope of the question, as OP asks only what the definite article means in this context, and not whether the definite article is required.
Best Answer
You can't really say he is world's greatest chess player. Nor can you say what in world are you talking about. The sentences are just not grammatical. You absolutely must have a definite article placed in front of the word world. That's because it's usually a requirement that you use some sort of article in front of countable nouns in English and if the thing that you're talking about has already been mentioned, or is common knowledge, or is about to be defined, the article to use is the.
However, it's a totally different story when it comes to the way we use the word Earth. You can leave out the the from the Earth (notice that this word usually begins with a capital letter). But in that case, what you're doing is that you're referring to the planet we all live on by its name. All planets in our solar system, as you probably know, have been given names: Mars, Pluto, Venus, Jupiter, Neptune etc. Earth is just one of them. Earth, in this respect, is a unique word as it can be used both with a definite article (the Earth) and without one (Earth).
As per the article that you've been reading, the fact that there is no definite article in front of the word world is simply a grammatical mistake on the part of the people who wrote it. Simple as that.