I have got an external LiveID user on my SharePoint Online site, which is still in the first-month trial mode. I assigned this user an Office 365 Business Premium License on my site and then sent him an invitation to my site. After accepting the invitation, the user can view the site in a browser, yet he cannot access the site programmatically, using C# code. The site returns Forbidden 403. Is programmatic access allowed in my scenario? If it is, what other permissions do I need to grant to this user?
External users are not able to programmatically access another Tenant environment.
- If you have licences, create account in your environment and assign licence to this account, set account as SharePoint Administrator at least
- Register Application on SharePoint and he can edit code with using ClientID and ClientSecret