This has to do with Orion permissions rather than Linux permissions.
Can you view the contents of the project folder in Orion? If not, this may be due to a bug in Maqetta when first creating users and their workspaces/files (should be fixed in M10; WAR for that release coming soon).
As a workaround, you can also download a ZIP from with Maqetta. From the Files view, click on the first icon in the toolbar ("Download Entire Project"). You can choose to also download the associated libraries, or just select None to disable them and only download your files.
Javier
- maqetta team