With an Office 365 subscription that start at I think $8/mo per person you get SharePoint, Lynch, Office (always the latest version), Exchange, OneDrive and more. So you can I'm not the biggest proponent due to privacy and storing things in MS's cloud, but a lot of companies that are on it really like it and it's relatively easy to use. It's designed to do exactly what OP is asking and works anywhere not just in the Office. Make sure, however, to read the privacy and third party access docs. They are HIPAA/HITECH compliant and will provide a partner agreement for it.