Set Author role to edit gallery

Hi.
I’m using Woow Gallery and I have e little issue: I need a user with role Author to edit a gallery. For website security reasons I won’t add Admin role for my client only for editing a gallery.
I could not find any option to set a role or a user to edit it, even setting him as gallery owner. It’s a common gallery and not a dynamic one.
How can I provide gallery access to my client? (he must be Author, but I also tried with Editor role, unsuccessfully)

Thanks in advance.
Regards.