need to help my 4 year old with his talents

For music, try to enroll in a music class for young children. See if he takes to a particular instrument. There are some instruments that have miniature versions (e.g. violin) for kids that age, but are still fully capable as musical instruments. If you don't own a piano, it might be good to have an electronic keyboard available. If he has a natural talent in music, he may well be able to learn how to play several instruments over the course of his development. When the time comes, make sure that when you get him a music teacher, they are familiar with and sensitive to his condition. A good, compatible, music teacher could do wonders for his self confidence and growth, but a bad teacher (meaning they aren't sensitive to the way he learns and perhaps overly critical) could turn him off music forever, so be sure to sit in on lessons (which you may have to do anyway, given his age). When he is old enough, playing in a music group with his peers can be a very positive way for him to develop social skills without overwhelming him.

For maths, try to find toys to develop that talent. Construction sets may be particularly fun for him. Consider toys that are designed for older children, as long as you are sure he is past the stage of putting things in his mouth.

I'm not sure how you feel about electronic devices, but there are apps for developing mahematical skills (though these will likely develop quite well on their own just from his observations of how the world works), and there are also apps for language skills so that he can catch up in that regard.

I'm answering not as a parent but from personal experience of having those particular talents as a child.

For music, try to enroll in a music class for young children. See if he takes to a particular instrument. There are some instruments that have miniature versions (e.g. violin) for kids that age, but are still fully capable as musical instruments. If you don't own a piano, it might be good to have an electronic keyboard available. If he has a natural talent in music, he may well be able to learn how to play several instruments over the course of his development. When the time comes, make sure that when you get him a music teacher, they are familiar with and sensitive to his condition. A good, compatible, music teacher could do wonders for his self confidence and growth, but a bad teacher (meaning they aren't sensitive to the way he learns and perhaps overly critical) could turn him off music forever, so be sure to sit in on lessons (which you may have to do anyway, given his age). When he is old enough, playing in a music group with his peers can be a very positive way for him to develop social skills without overwhelming him.

For maths, try to find toys to develop that talent. Construction sets may be particularly fun for him. Consider toys that are designed for older children, as long as you are sure he is past the stage of putting things in his mouth.

I'm not sure how you feel about electronic devices, but there are apps for developing mahematical skills (though these will likely develop quite well on their own just from his observations of how the world works), and there are also apps for language skills so that he can catch up in that regard.

I'm answering not as a parent but from personal experience of having those particular talents as a child.

Thank you very much for the detailed advice.