To create music you need a certain, even if very coarse and asystematic, understanding of mathematics.
I believe there are many musicians now and have been many more in the past with none.
Anyway, what do you mean by an asystematic understanding of mathematics? To my understanding, mathematics is a formal language for reasoning about the specific kinds of tautology that the language is able to express.
Some features of music, e.g. harmony, rhythm, pitch intervals have been approximately represented in mathematical systems that can be analyzed and manipulated but such modeling is, I believe, outside of the practice of music itself and not necessary to it. Math is added on to music by those who choose to or have to because of how they are taught. (And some musicians have incorporated math into their creative process but this is as unessential to music itself as incorporating Schiller poems.)
Remember that while "Western" music has theory (of sorts*) that's taught to most pupils, that's not so in all music traditions. For example, musicians in Hindustani music, a tradition that's identified as a singular real thing for over 1000 years, learn without theory(**). Also look at how a number of expert scholars, skilled in mathematics, have tried to model that music and have been unable to get very far. They can't even agree how many pitches are involved (which suggests to me that trying to count them is asking the wrong question).
(*) It has some uses, principally to allow practitioners to communicate more efficiently, but musical creativity, it seems, usually involves breaking its rules, i.e. doing things the theory can't usefully say anything about.
(**) A TV series from 1992 has these two segments I cued up for you. The whole thing is really wonderful and worth a look for anyone who cares about music. Here the teaching process is stated as:
imitation, repetition, exploration. If there is a unifying theory of human musical traditions, I guess that's closer to it than mathematics.
- One
- Two