This is because Zoom has introduced an encryption that older versions cannot handle, so you need to update your Zoom app.

This applies to Windows 10:

Uninstall your old zoom app first. There are many ways to do that, one is to right-click on the Zoom icon in your start menu and select "Uninstall".

When the uninstall is complete, restart the computer.

Reinstall Zoom

• Select "Client for meetings" that you can find here: https://zoom.us/download#client_4meeting
• Download the file and run it.
• When the installation is complete, you need to log in: Start Zoom and select "Sign in ", in the next box, select "Sign in with SSO".
• In the box that follows, "Company domain", type: du-se
• Then log in with your username and password as usual.