Solution

1. Call the context menu, you can right-click and select the "Properties" menu item, then find the sub-item "Sharing and access rights" (at the very bottom).
2. Find in the list of your current user, if it is not in the list, add it by pressing the button on the screen "+".
3. Set your user the right to "Read and Write" and make it the owner by clicking on the user and selecting the "Make Owner" item.
4. Re-invoke the context menu and click on the "Show content" menu item and do the items 1,2,3 with the "Contents" folder and additionally apply changes for the attached files.
5. Launch the Pandorium Launcher.