Unable to use Gitlab service account

I'm trying to connect my Stoplight account to Gitlab using a Gitlab service account, with the end goal of being able to have changes made in our git repo automatically publish into Stoplight. I've read through every doc I could find, and all of them state that to do so I should:

1. Create a Git project
2. Edit the project settings
3. Select Gitlab as the provider
4. Enter the service account and token

The problem is that I can't seem to create a Git project without entering Git credentials, and the only way to do that during creation is via an OAuth flow that requires logging in to Gitlab. The problem there? Gitlab service accounts can't be used to log in to Gitlab.

I'm trying to avoid using my own Gitlab account for this because I don't want Stoplight to have full access to everything in there, so a service account seems like the right solution... except that I can't actually enter the service account credentials anywhere.

Any ideas? Please help! Thanks so much.