MOOCs have emerged as an important form of Open and Distance Learning. The success of a MOOC platform depends on the support services and the motivational environment that it provides. This paper presents a comprehensive picture of the literature on the motivations that drive learners to enroll in MOOCs, published between the years 2011 to 2020. In this study, an attempt has been made to examine various research papers, for identifying key motivational factors related to the learners, platform, course and facilitating conditions for enrollment in MOOCs. Using the systematic literature review strategy, the papers are classified based on the technologies adopted to facilitate the discovery of directions displayed by the available literature and determining the current gaps, so that they may be addressed in the future. It was further found that various important hidden factors are still untouched or has limited literature on them, which makes MOOCs system successful.