Backup ]project-open[ to Hetzner Backup Server

We run multiple ]project-open[ instances which need to be backed up regularly to a hetzner backup server. To backup ]project-open[ we already have backup scripts, but the main drawback is that they zip a complete copy of the ]project-open[ directory and then transfer one big file over to the backup server. This is due to the fact that RSYNC does not work with hetzner backup (see [login to view URL]). My expectation would be that we make a full copy of the ]project-open[ directory to the backup server without copying over every single file but only the new and changed files. Additionally we have a secondary server which runs the staging environment. This one should also receive a copy of the directory, which should be a clone. Again, only transfer changed and new files. Here RSYNC is possible directly. We are talking about four ]project-open[ instances for which this setup is needed. Additionally a quick documentation needs to written how to do this properly, so it is easy to set this up for future servers.