As Saga Musix points out, the tutorial was written with 2 things in mind. Teaching you how to use the program foremost so you can start fiddling with it yourself afterwards, and giving a few tips that will get you started.
The tutorial was designed to get anyone started that has:
1. A computer capable of running OpenMPT, and
2. Able to read English, so they would understand the tutorial.
Yes, no music theory is necessary at all. If you have it, it will help you in the long run, but if you don't you still will get the hang of it eventually.
Music is like a sport. The more you do it, the better you get at it. The road of improvement is gradually though. Each song will get you slightly more experienced and if you make 20 songs, after the 20th song, you will have developed skills and will be able to hear an improvement over that first of 20 songs.
You are now tracking for 2 years, so in musical terms you are still a beginner. When I was tracking for 8 years, I finally started to feel that I no longer was a noob at making music, and actually got past a barrier. Yes, it took me that long, but that was probably me, and it also did not help that for the first years, I was not involved in any community. I just made music because I wanted to make music. Its fun.
That said, when I was in those stages, I was very careless in making music. I mostly made half-finished songs or just short ideas and almost never really finished a song. Finishing a song is a skilled I learned like 4 years in. Before that, I had songs that had an end, but they were not really songs. They were projects with an idea that eventually either just faded out or had some weird ending.
And you know what, that was perfectly okay!
As for learning the correct way, the answer is really simple. After you made a song or part of a song and you listen back to it, do you like it yourself? Yes? Then that is the correct way.
In music, you come first, the rest comes second. Once you get so good that you want to start making money with music, only then others will come first, but once you get there, you actually have the necessary experience and skills to make music that you know others like.
Do you need musical theory for all this? It'll help, but no, you don't need it. All you need to figure out, is that whatever you make sounds at least okay. If you like the song in the end, then you accomplished something.
Now, that said, if you feel like you are stuck, and you probably have little inspiration, it is time to expand your bubble. Step out of your comfort zone, and try something new. Are there other music genres you really like? Try making a song in that other genre. Having a hard time? Try to recreate a song you like. It doesn't matter that you "steal" the song. If you don't release it, it is fine. It will be your method of dissecting a song in order to learn its secrets.
Another thing you can do is break down music in various parts. For example: drums, bass, melody, background, effects, etc. Then focus on one of these for a song and make that part the best you can, where the other items are just there to help you fill the song.
If you choose drums, then try to make the drums sound as great as you can. Don't just use a basedrum a snare and maybe a hihat. Go look into what a drum actually is. How is it played in reality? Can you emulate that? Can you figure out something with drum samples that works for you and makes your drums sound really good to you?
For example, if you have a drum, you can lower its volume for an echo effect. You can also skip playing the first bits of the sample (Offset effect) to dull the hit. Combine these and you can get very analog with the drums allowing you to fill emptyness with drum sounds without becoming the main thing. And believe it or not, sounds you barely hear will be missed when absent from a track. (this last sentence is true for any sound in your song btw)
