It says All rights reserved on modrinth but can I modify it a bit and use it in my private server?

Somebody correct me if I'm wrong, but "All Rights Reserved" means that Ladysnake decides what can and can't be done with other people distributing it and modified versions. However, by using it server-side on a private server, you're not distributing it, and you are allowed to modify that. However, you're not allowed to publish that anywhere without Ladysnake's permission.