The documentation is very lacking (probably because this is new?) and it took me some extra time to figure out where to get the tokens and how to configure the importer.
When you run this step gh actions-importer configure
you need to provide personal access tokens for both github and the platform you're trying to migrate from.
In my case it's Travis CI and that's what I will cover here, however the steps to acquire the personal access token for github are the same.
Tl;dr go here: https://github.com/settings/tokens