Sharing files securely
There are many different ways to share files with others. However, not all of them are safe. Free tools may sound appealing, but there's no such thing as a free lunch. Downsides may include your data being made accessible to others.
Teams
Through Teams, of course, you can securely share files. This is part of the Microsoft Office 365 package.
SURFfilesender
SURFfilesender is secure and does not view your data. So this is the most secure way to send (large) files, optionally encrypted.