connect to relative remote iMac via finder hanging

I want to connect to my Mother's mac mini computer (who lives in another state) via the "Connect to server" so that we can transfer files over the network. This is the first attempt so forgive me for my basic knowledge on this. When I enter in the server address I click connect and it just hangs. Is there any other configurations that need to happen in order for this to work? I have tried using the address that is displayed in System preferences and as well as her apple ID. She has Remote Login turned on and remote management and file sharing but for some reason it hangs as if it is trying to connect but nothing happens. Is there any other configurations that need to happen in order for this to work?

Since Apple removed 'Back to my Mac' from the system, it's been harder to get structures like this to work for the average home user.

The primary issue is that you need to use port forwarding on the remote router - not insurmountable, unless it's your 80-year-old technically-challenged granny who needs to set this up, 2,000 miles away. [Been there, done that].
Even if you are able to set up port forwarding, because you are setting up commonly-used ports & protocols, you will then find you get a constant stream of random remote requests coming through it, from chancers trying to find a weak spot. You can't lock it down to requests from a specific IP address, because consumer IP addresses can change at any time.

So… forget that idea.

Instead, look at something whereby each user connects outbound to a remote server, which can then allow them to perform a secure handshake, then hook up directly to each other, without your firewall getting in the way.
It is far easier to see out through a firewall than try to punch a hole in. It requires no technical expertise from the user. Your browser does it every day.

There are many solutions to this problem, & the first one that always springs to mind is TeamViewer. I've used it, many years ago, it worked just fine. However, if they ever think you're using this for corporate purposes, they lock you out, rather unforgivingly. I eventually gave up trying to persuade them that one set of parents lived 200 miles in one direction & the other set 2,000 miles in the opposite direction, in a different country.

So, you could try TeamViewer, or one of the many alternatives that have sprung up over the past 10 years.

I normally don't like posting links to online comparisons as they often seem to be only trying to sell you their own solution rather than being fair & even-handed, but this one does appear to be un-biased. Ionos - Alternatives to TeamViewer
Most of those have free versions for home users, so pick one by feature-set; which looks the most useful to you. I'd probably go for AnyDesk these days, partly because it's supported on most platforms but also because it's made by a splinter from TeamViewer & aims to be faster, but I've not yet tried it so I can't honestly say which would be best these days.