Pre-university mathematics enabling courses can potentially change adult learners' perceptions and beliefs around mathematics, enhance self-efficacy, personal confidence, motivation, and enable achievements that support future study and career goals. Enabling courses, however, often require highly individualised curricula and approaches that can be complex to deliver. To explore the factors that engage adult learners and effective approaches to enhance adult learning, a scoping literature review was conducted to understand the extent and nature of peer-reviewed studies into adult learning in mathematics from the last 10 years. From analysis of the 23 selected articles, informed by the ideas of andragogy, three key ideas emerged: (1) adult learners' confidence and readiness to learn; (2) adult learners' motivation and prior experiences; and (3) adult learners' need to know and orientation to learning. The scoping review offered insights into effective approaches for developing self-directed learners, such as learning design for flexibility, social connections, collaborations and step-by-step teaching for adult mathematics learners. Specific strategies such as the use of checkpoint and activity-based learning were also found to support engagement. This study has implications for individualising adult learning of mathematics in enabling courses in universities.