At the beginning you have to go to the Sdui Cloud. To do this, go to the "More" area in the footer.
Now click on the cloud tile.
You will now see the following picture:
Select the group in which the file was shared. All files that were shared in this group will now appear.
When you have found the file you want, click on the three gray dots and then on download.
The file will then be saved on your device.