With The Sims 4 Create a Sim Music being divided into 2 parts – Mild (when you go into Detail Mode) and Normal (when choosing Clothes and such), Youtuber Vitor Pires provided the Mild part of The Sims 4 CAS Soundtrack. Please note that CAS Music #5 is from The Sims 1.
Click Here to listen to the Soundtrack! (YouTube)