Generally speaking, your music sounds very amateurish – by that I mean that basically every aspect, from composition to production/mixing is lacking in quality. The samples and guitars sound cheap and “unproduced”. For example that sound in your last track, 15 seconds into the track sounds extremely cheap and conflicts with the piano. The piano itself is not great either, and the flute-type thing 40 seconds into the song is really bad, too. These are just a few examples where your music is just not up to par with current standards here at AJ. You might want to listen to some modern music to get a better feel for what sounds are in play these days.
Moving on, your mixes sound flat, have no depth, no punch, the instruments are not well mixed and everything does not sound coherent.You need to work on your mixing skills and develop an ear for frequencies and sounds. Same for effects/reverbs/echo: Try to read up on how to use them.
Finally, the music. Here at AJ music has just one purpose: To help video creators deliver their message, easily and quickly. That means for you: No long intros, no soloing, no complications, getting to the point quickly and making interesting tracks for specific tasks. Right now, your tracks sound like you simply sat down and recorded yourself playing what you like to play. That is perfectly OK, we all do that for fun and to express ourselves as artists. But, if you really want to compete with thousands of authors already here, you really need to think from the buyer’s perspective. You need to be modern and relevant.
I would suggest that you spend some time going through the tracks at AJ, find a few tracks that suit your style and that sell well and really listen to them, compare them the sounds they used with your own, find out what works, and why. Then try to use what you learned in your own music. It will take some time but you will get there. Good luck!