In that case, you have reached the execution phase. During the placement or coaching for it, or practical vocational training (BPV) or a graduation period, steps from the step-by-step plan are not automatically opened anymore.
You can do this yourself (if the step in question is intended for you) by clicking the name of the step in the activities tab or by clicking on the step in the 'not yet started' groups. The sequence of the steps is no longer mandatory; you can therefore open multiple activities at the same time.
Steps that are not intended for you but for someone else, have a paler colour showing that you can therefore not open them.