Allow webserver access to specific folder

I’m using a 4TB WD My Cloud model number WDBCTL0040HWT-NESN.
For a web app project I would like my PHP application to have access to a data folder on the My Cloud, but this doesn’t seem to work. With my normal user account that I’m logged in with (ruben) I do have access to the folder. On my Macbook I can access the folder from the terminal by cd-ing into /Volumes/Public/Work and I can access the files in Finder as well.

From my web application basic file operations don’t work and I think it’s because of a permissions issue.
Apache is running under the _www user account, but I can’t simply chmod the Public folder to allow this user access. Is there any other way I can make a folder accessible to every user?
The UI tools that came with the My Cloud don’t seem to have this option either.

Hi,

I’m pretty sure the UI gives you the option to change permissions on a Share, and also access or deny permissions for all users created.