Office 365 (SharePoint) - Sharing files/folders to external recipients
When sharing files on OneDrive or SharePoint with specific individuals (not via anonymous links) outside UWM, recipients will need an Office 365 account, a free personal Outlook.com account, or a Microsoft account associated with their non-Microsoft email address in order to view the file.
Please see Microsoft's document on how to sign up for a (personal) Microsoft account. for information on this process.
If the external sharing recipient already has a Hotmail account, or an account for a Microsoft service such as OneDrive or Xbox Live, they already have a Microsoft Account and can use that account to sign in.
After signing up for an account, external recipients can then access Microsoft online services such as Word, Excel, and Outlook.