How to add user outside my organization?

[Lebowski]

I need to add a ArcGIS Online User to my ArcGIS Online Group. My group is setup through an organizational account, however, the user I am trying to invite is a member of a different organizational account. They just recently became a member of their organizations, organizational account. I have tried searching for their name but I am not seeing it.

Any tips and/or directions to get invite and/or give them direct access to my ArcGIS Online Group?

Thanks

[Katie_Clark]

First off, are you the owner of the group? If so...

From the group page -> Members Tab:

When you click "Invite Users", have you unchecked "Only search for members in [organization name]"?

[Anonymous User]

Ask the user to check if their profile is set to public.

[ChristianSailer2]

How can I automate this with external users (outside the subscription) without requiring confirmation using ArcGIS API for Python | ArcGIS for Developers ?