I have a similar configuration like the one described above just that in the documentation you are referring it doesn't state what should I do if I'm using FileZilla, I only get instructions for winSCP:
If you need to upload files to a location where the bitnami user doesn't have write permissions, you have two options:
Once you have configured WinSCP as described above, click the "Advanced…" button and within the "Environment -> Shell" panel, select sudo su - as your shell. This will allow you to upload files using the administrator account.
So what should I do in order to be able to upload files through FileZilla?