Need someone to make something like dropbox for my own use

I have a virtual server that is hosted here in South Africa with over 200gb space. I need something similar to how dropbox works. . Basically files that get changed on my laptop should sync to various computers that are not part of the virtual server network. These computers may be in another network that is external. and my laptop may be on another network also. Files need to be stored "in the cloud"(on this virtual server) but should appear as normal files/folders on each pc. Each pc can have their own email/login and only i can assign who has read only rights or read/edit rights. There may or may not need to be an actual application for this. I do not want to use things like FILEZILLA as i do not want to copy files each time i edit them.