Inside of MEP in the Effects section you should see an icon for it. Clicking on the icon should then give you a download button to the right. Once downloaded, go to the link that will appear and register with NewBlue and make an account and activate from there. It is vitally important you keep all email login details and any registration codes you receive via email safe for future use in case your system fails in future. That includes any for Movie Edit Pro or you may not be able to download the products again at a future date.
If you used the update from MEP 2020 (judging from you screenshot) then that effect is not included in an update. Updates only include the program and the effects you had at the time of purchase.
That can be found it the user terms and conditions on the Magix website. I know most of us are confused and disappointed at first.