Hi Priya,
About the external users, I would like to explain that if we share a site or a file with an external user, the external user can access it via the invitation email. Then, the user profile for this user is created and the user such as emailaddress#EXT#@defaultdomain appears in Office 365 Admin Center > Active users as below. We can’t add bulk external users to the Office 365 admin center.
There is no command to add bulk external users to a SharePoint site. We can add external users one by one via Site settings > People and Groups > Site members > New. After they access the site, their accounts list in
Site Member.
As a workaround, we can create an External Users group in the SharePoint site via Site settings > People and groups > Groups > More > New. Then add multiple external users into the group and share files in the site with this group.
Regards,
Shirley