The paper provides a comprehensive review of NOMA-aided cell-free massive MIMO (CF-mMIMO) systems, which are emerging as potential solutions for future 6G networks. The authors discuss the benefits of CF-mMIMO and NOMA, including increased connectivity, low latency, and improved spectral efficiency. They present a detailed theoretical review of mMIMO, CF-mMIMO, and NOMA, highlighting their key features and challenges. The paper also reviews the integration of these technologies, discussing the challenges and potential improvements in performance when combining them with other enabling technologies such as RISs, radio stripes, and machine learning. The authors conclude by discussing the key findings and future research directions in the field.The paper provides a comprehensive review of NOMA-aided cell-free massive MIMO (CF-mMIMO) systems, which are emerging as potential solutions for future 6G networks. The authors discuss the benefits of CF-mMIMO and NOMA, including increased connectivity, low latency, and improved spectral efficiency. They present a detailed theoretical review of mMIMO, CF-mMIMO, and NOMA, highlighting their key features and challenges. The paper also reviews the integration of these technologies, discussing the challenges and potential improvements in performance when combining them with other enabling technologies such as RISs, radio stripes, and machine learning. The authors conclude by discussing the key findings and future research directions in the field.