Microlearning is gaining ground in the higher education domain. Despite this trend, there is a lack of evidence of effectiveness when a large number of microlearning units are grouped to form a macrolearning programme. The purpose of this paper is to explore how and why a macrolearning affects students' self-efficacy. The originality of this paper is its in-depth analysis of an EdTech startup named MLMaster, which has built a portfolio of several business programmes, each consisting of over one hundred microlearning units, forming macrolearning programmes. The main contribution of this paper is to uncover critical insights into how self-efficacy is built in practice, driven by two main factors: participants' affective states, which are the positive feelings after taking part in the programme, and mastery experiences, which is the application of learning at work.