Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

I tried creating my own torrent and was able to dl it on another device, but on her machine it stayed at 0% and wouldn’t let me connect to seed

At least one of the torrent clients needs to be fully connectable (port forwarded) for torrents to transfer data. You need to test that e.g. test your torrent client's incoming connection port with a port test website like https://www.canyouseeme.org, https://www.yougetsignal.com/tools/open-ports, etc. & make sure those port test websites can successfully test connect to your torrent client's incoming connection port. If the test fails then you need to look at opening the port via your OS firewall and/or router firewall.

Is FTP a good option? I set up a proxmox server last night but I don’t really know what I’m doing yet

Probably best to avoid FTP if you don't know what you're doing, it's not all that secure.. you'd want to at least configure SFTP or FTPS which is just going to be more complicated vs fixing your torrent issues. And technically you still need to make those connectable (port forwarded) too, just like your torrent client.

All that aside it's probably easier to use Syncthing if you can't get the torrent working.

You could also try one of those file transfer websites that use WebRTC to transfer data peer to peer e.g. https://file.pizza or similar. Not sure how well they work for huge amounts of data but their github page mentions that Firefox is better for that, apparently Chrome starts to choke with data 500+ MB.

I would use syncthing for this

Could send it over ATP - Avian Transfer Protocol.

Does require a USB stick and for your friend to train a pigeon though.

I use Syncthing for this things, you can even set a folder and keep it in sync with multiple users because it uses P2P

Syncthing

Easiest and most secure way? Mail (or hand deliver) a flash drive. That's how they transfer data between super computers and data centers. (AWS even has dedicated trucks to do it)

Don't put FTP on the Internet if you don't know how to secure it.

If you're relatively nearby, you could just use a flash drive. Or mail one. If not, the other comments have good suggestions.

maybe SimpleHTTPServer (python) on the host and curl -C on the other machine?

Create a multi-part archive (...probably about 250 parts...) with a strong password, upload each part to whatever the current equivalent to Megaupload is, and let them download it at their leisure.

With no accounts on either end, should only take about three months for each to be complete.

Alternatively, you could put it on a thumb drive and drive it over if they live fairly close.

In one go? Look at Wormhole

But both ends must stay online until it is complete.

I would use Resilio Sync. It uses bittorrent under the hood. https://www.resilio.com/individuals/