I have created a new team site inside sharepoint online. Then i defined the site to be Public + to allow external sharing as follow:-
But when i wanted to share the site with existing external user (who have access to a classic team), i got this error message "could not add **** as member", as follow:-
so can anyone advice on this please?
Final note. note sure if it is related to my problem. But when i access the group (which got created automatically after creating the above team site), from the office 365 admin site, i got a message that i can not modify the group's properties due to permission (although i am sign-in as the office 365 admin):-