Can I put the music that I have bought on iTunes on my Samsung phone?

If you bought the downloaded tracks later than 2009, they are in normal AAC format and can be used on a Samsung phone. If they are Apple Music subscription tracks, they cannot be used.

Assuming the audio files are on your computer, follow the instructions for the phone. If you have lost the downloads, you may be able to get new copies free:

Redownload apps, music, movies, TV shows, and books - Apple Support