Can't get stackeditDOTio to synch with GitLab

I’ve tried using this GitLab Help page to enable stackedit.io to connect with a GitLab repository I created for the purpose:

https://docs.gitlab.com/ee/integration/oauth_provider.html

I’ve tried different URIs and so on and all I get is:

An error has occurred
The requested scope is invalid, unknown, or malformed.

Q: Is the URI I submit to stackeditDOTio my base GitLab URL (https://gitlab.com/WritingSolutions2020) or do I need to supplement that URL with /users/auth/gitlab/callback as seems to be suggested by the GitLab online help page?

2020- 04- 28_ 0824 StackEdit

Q: Is the callback URL I specify when creating the stackeditDOTio application the one given in the stackeditDOTio Link Your Application dialog shown above https://stackedit.io/oauth2/callback?

The online page also refers to Admin Mode. I’m unable to access that – among other things I don’t get the wrench / tool icon shown in the OLH page’s screenshots.

Thanks in advance,
Riley
SFO