A instructor in our community college is trying to create a survey using Office 365. The link https://support.office.com/en-us/article/Surveys-in-Excel-hosted-online-5fafd054-19f8-474c-97ec-b606fcda0ff9 explains the steps. When the instructor tried that, he got a message "Sorry, you can’t create surveys here".
Our server admin for Office 365 feels, to make it work, we need to turn on "Allow both external users who accept sharing invitations and anonymous guest links" on both Tenant and Site Collection Levels.
He feels the potential risk is that everyone can use OneDrive Excel Survey to create and share files and folders to external users and the external users then can access our Office 365 at some level.
Is there a way to stop external users from accessing our Office 365 in any level?
Even if external users are sent such surveys, to what level can they access Office 365? Is it risky enough to not to use Excel surveys?
If it is risky and such Excel surveys should be avoided, are there any other methods using Office 365 which do not have any risk?
Is the risk reduced or eliminated if the people to whom Excel surveys are sent are students in our community college?