You followed the right steps. I have found that sometimes retrying it works, but if it keeps failing, you may have to authenticate with a username and a token (you can generate one from the old repo).

Also what's the difference between importing the repo vs forking the old one

Forking a repo is creating a personal copy but with link to the original repo, this way you can make changes on yours safely.
Importing does this but without pointing to the original.