Login to Office365 Admin Portal

Portal.office365.com – https://admin.microsoft.com/

In Microsoft 365 Admin Center

Go to Setting

Under Service – Go to Office 365 Groups for Manage external sharing

Click Office 365 groups

Now here make sure the first & Second options “Let group members outside your organization access group content” is selected.

Else external / Guest users wont be able to access group content.

“Let group owners add people outside your organization” to groups is selected.

Else Team Owners wont be able to add guests

Thanks,

Praveen Kumar

Microsoft Certified Trainer – Cloud Services