Since February 2020, due to COVID19 pandemic breakthrough and the constraints it brought, the delivery of the training offer have deeply changed: consequently the entire training activity of MaX has been remodelled in order to organize schools and hackathons only on online digital platforms. Both teachers and students had to work hard in this new scenario, learning new ways of delivering training on one hand, and giving up all the benefits of in-person learning on the other. Nevertheless, two positive aspects in this frame have emerged: the fact that online training activities remove travel barriers, overcome logistical limitations, and expand the audience of students; then the need for preparation of online training material that remains available beyond the time of schools, conveniently available for all interested. In this booklet, the readers will find the collection of all the online events organized by MaX in 2021, mainly focused on the theory, implementations, and use of the most used MaX flagship codes (Quantum ESPRESSO, Siesta, Yambo, Fleur, AiiDA) in the HPC environment. For each school, a dedicated section describes the organization and the main objectives of the event; then users will find all the links to the available material prepared by the MaX trainers, such as the complete recording of the lectures, the slides, and the online tutorials that students can follow at their own pace.