From the Terms of Service:

Moreover, by submitting or posting User Content to the Service (either directly or through a Third Party Service) you grant GTA5-Mods.com a royalty-free, perpetual, irrevocable, non-exclusive, sublicensable, assignable, unrestricted, worldwide license to use the User Content, together with all consents or waivers (if any) necessary to reproduce, distribute, publicly perform, publicly display, transmit, communicate to the public, modify and make derivative works of the User Content, by any means and in all media formats and channels now known or hereafter devised in perpetuity, and to advertise and promote such use, without further notice to, or permission from, you or any other person, and without compensation or reference to you or any other person.

That means you give GTA5-Mods permission to use the content, but GTA5-Mods does not own it.