No permission to upload or create files here

After installation of owncloud, I try to upload a file to the owncloud but I’m getting permission issue:

All the users including admin are not able to upload any files.
This is the first time I’m using owncloud.
This is my settings:

I also have MySQL and nginx installed.

please share related owncloud.log entries. The file is located under data folder.

owncloud.log (13.1 KB)

this is the file