Chosen Solution

In the previous macOS High Sierra I think … it was easy to add dzwonki na telefon to iTunes and sync them with your iPhone. But now in Catalina, how should I do this? (there’s no Tones tab within Music aka the former iTunes)

Here’s a great how to guide on that! https://www.howtogeek.com/469085/how-to-

Essentially, you still use itunes to do it (or any other software that can create .m4a files). Then you change the file extension and drop it to yourself and you’re all set!