It's fine if you skip the onboarding guide and prefer to setup repo manually.
To setup manually is also the recommended way to sync with private repos.
Sync Public Repo
Setup Repo Url
On your repo's settings page, copy the HTTPS based Git Url. For example,
Back to GitPress, visit article's settings page or collection's setting page. Tap "Manually setup", paste the Url.
Tap "Save" button.
On your repo's settings page, copy the Webhook Url
Visit your repo's webhook settings page at GitHub, Tap "Add webhook"
Fill the Url entry, and Tap the green button "Add webhook" at bottom of the form.
On your repo's settings page, Tap "Rebuild" button
Sync Private Repo
By default, GitPress can't access your private repos.
If you want to use private repo as posts source, you need to follow the instructions above to manually setup and do an additional step to complete.
Setup Repo Url
Because GitPress can't read private repos, you should tell GitPress which private repo you are want to use. See the instruction aboved.
GitPress has no permission to create webhook on your private repos, you have to add webhook your self. See the instruction aboved.
Add Deploy Key
To read the content in your private repo, GitPress is asked for a deploy key.
GitPress has generated a deploy key at settings page for each private repo. Copy it and visit your private repo's deploy key page, tap "Create deploy key".
Fill the form: paste the key into the textarea, and type a name for the key.
Tap "Create deploy key".