In 2000, after graduating from the Faculty of Economics and Business in Maribor, Branka Mlakar-Štok began working at IZUM in the User Services Department. Until 2003, she conducted training courses on the use of the COBISS software, primarily in the areas of loan and loan statistics.

She actively participated in collecting librarian data to establish the Central Register of Users and in developing the Training administrative application. In 2005, she joined the Training department, where she coordinates the implementation of courses and ensures the smooth running of training programmes. She participated in the preparation and development of the Training portal, which in 2007 enabled online registration for COBISS courses. She also participated in the transfer of procedures for creating usernames and assigning permissions from the COBISS3 software to the Training portal, which was launched in 2009.

In 2017, she participated in a project to integrate school libraries into the COBISS system, primarily focusing on operational tasks and the creation of usernames for working in COBISS.

Since 2017, she has been collecting and analysing statistical data on training sessions conducted in the COBISS.SI and COBISS.net systems.

In 2023, she took over as head of the Training department.

In 2025, she actively participated in the project to revamp the Training portal and transform it into the COBISS Edu librarians’ portal and the COBISS Edu website, as well as in the transformation of the administrative part of the Training application into the new EduAdm application. The revamped COBISS Edu portal, the COBISS Edu website, and the EduAdm administrative application were launched in December 2025 for the COBISS.SI and COBISS.net systems.