If your manager uses this feature, you can pick up open shifts. An open shift is a shift for which there is no team member scheduled yet, so you can you pick it up. You do have to meet the following requirements:
You need to be part of the team of the shift or have the same function.
You are not scheduled to work during those hours yet.
You can only pick up open shifts through the app. You can find them in two places:
In Requests > Trade overview > Inbox > click on the request.
In Shifts > Schedule > on the day with the open shift > click on the shift.
If the manager also sends out notifications, you will receive a notification for an open shift.