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Dear Michelle Alonso,
Thank you for update.
I noticed you can open it via OneDrive for work or School, but you can’t open it via personal OneDrive. And you mentioned that the file is set to "accessible except for external users".
This may be an issue caused by permissions, your personal account is an external account, and you don’t have permission to access these files of your business account through your personal account.
For more personal OneDrive questions, I recommend posting to the For Home category. Since our category focuses on the basic features of Office 365 Business Edition products and we can’t assist you further on personal OneDrive.
Thank you for your patience and time.
Sincerely,
Claire | Microsoft Community Moderator