Backing up ReadyNAS to another ReadyNAS in a remote location

Hi all, ReadyNAS newbie here hoping for some guidance.

My employer uses a ReadyNAS system in the office for data storage, and every night, it backs up to another ReadyNAS (same model, I believe purchased at the same time) located remotely at her house over ReadyNAS Replicate. Lately however, it stopped backing up and I (as resident sometimes-IT-guy) took a look at it. I updated both models to the current firmware and was able to transfer files over the local network, so passed it along back to her to set up at her house.

Unfortunately, my networking knowledge is slim to none, and I cannot for the life of me figure out how to connect to the remote ReadyNAS's admin page from work, not to mention setting up a new backup scheme that no longer uses Replicate due to that service ending soon. Complicating all this is that the remote ReadyNAS gives a local IPv4 address, but when I asked for her public IP address (using her phone to look it up), it came back as IPv6, which I honestly didn't even know was a thing until now.

Looking at the admin page for the local ReadyNAS, I am also unable to find a public IP or other means to connect remotely to it.

Currently, I'm guessing that I will need to create a ReadyCLOUD account and connect the two devices to that, but all the help files and FAQs that I have found make it sound as though that service is mostly for remote access of single files, like a non-enterprise Dropbox account, which isn't really what I'd need. I was hoping to use the rsync over SSH protocol, but without a public address or means to connect remotely, I'm not certain that would even work. Or am I completely off base?

I obviously lack a lot of information, but am a pretty quick learner, so if anyone could even just point me in the right direction, I'd be much appreciative.