The global shortage of highly skilled employees has created a need for a more efficient onboarding process in software development companies. The experienced onboarding efficiency affects the new employee's willingness to stay within the company and the efficiency of their work. Our case company transferred to a team-based organization structure, where agile teams were given high autonomy. Supervisor responsibilities were divided among different roles, such as people coaches and a lead team. We studied the onboarding process through a survey that was answered by 39 persons, as well as 18 interviews to gather details from the onboarding process. To validate the findings, workshops, and presentations were organized in the case company. We found that mentoring was experienced as the most important form of onboarding in the case company. The biggest challenges were lack of transparency, insufficient material availability, and lack of documentation. As solutions were suggested: a shared repository of onboarding materials, checklists for teams and mentors for onboarding new employees efficiently, and collecting team-specific materials to a single location.