You have posted in the Movie Edit Now forum - is this the program you are using?
If not, what is the full name of the program that is asking for an activation code.
We need more information to help diagnose the issue(s) you are having:
The specification of your computer system including Windows version and program version, see this topic for what is required, and please quote processor and graphics card make/model in full, and also what monitor/screen resolution(s) you are working with if this is a laptop.
I would suggest you put this information in your profile signature so we do not have to keep asking for it.
Does the activation message appear soon after starting the program or adding video?
It looks like you have an older version Movie Edit Pro before it was rebranded to Movie Studio - what is the version number as found under Help, About?
It looks like you are trying to add a video clip that requires the HEVC (h.265) codec that requires purchase and installation, and you have entered an email address which is not being recognised as a valid account email address.
The email address should be the same one you purchased and activated Movie Edit Pro with.
I would suggest you contact Magix by email to infoservice@magix.net, asking them to check your account and why Movie Edit Pro 2020 (v19.0.2.58) is not connecting to the Store.
If you have recently re-installed the program because you have recently reinstalled windows or put the program onto a new machine, the old HEVC copy you had will no longer work or actually be on your machine and will have to be bought again from the Microsoft store as Magix do not own the HEVC codec so is bought as a third party licence. Microsoft in the past did allow the codec to be downloaded for free but that is no longer the case as they do not own HEVC either.