It would appear from your second image that the NB server does not recognise your email address, perhaps because you have not previously registered any NB app or perhaps you now have a different email address to one which you may have used previously to register an NB app?
If you click on the "cog", top right corner of the NB Activation screen, you have an option to contact NB Support. Given that this is a problem of an unrecognised email address I suspect only they can help you.
You talk about NB Filters 5 Ultimate which does indeed come with MEP2021 Premium. However, your image shows NB TitlerEx which has nothing to do with NB Filters 5 Ultimate. The same with your response from NB - you sent them the image of TitlerEX, which does not come with MEP.