You need to get registered at their website, build a profile and once there is a job vacancy they will contact the candidates for an interview.
Answered - IT/IS intern (Former Employee) - Johannesburg, Gauteng
Applying on their careers website works.
Answered - Engineer in Training (Current Employee) - Johannesburg, Gauteng
Diversified and comfortable
Answered - Site Manager (Former Employee) - Limpopo, Zambia, Mozambique, Botswana and Gauteng