To share files internally or externally, you can use Onedrive.
To share it, do as following
Open Onedrive (for example from the Waffle icon)
Navigate to the file or folder you want to share
Tick the file (or folder) and click on "Share"
OR
Click on the Share icon next to the name of the file
The "share" button will not appear if you have selected several files.
A pop up will appear
With the default option,you can send directly enter the email adres ( external or internal), provide a message or copy the link to send it in another or using even outlook.
Click on Send to finalize
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If you want more control, click on the "anyone with the link can edit" option to have more choice
