Dolphine error message?

I downloaded the Dolphine Emulator because I want to use it to play an old game from Nintendo on my PC. The game does not appear in the list on Dolphine. Every time I click on the game in my folder an error message appears (1st picture below). When I click on "OK" the next window appears (second picture below). What could that be?

What can I do about it?

Thanks in advance

You have to right-click to unzip the file beforehand.

OK thanks. How does it work?

As already written on the right click> Unzip ^^

It's not a zip file somehow. The item unpack or extract is not displayed.

Did you install Winrar?

The file is packed with 7z, if necessary download and install "7z", then right-click to display "unpack with 7z".

Here is the link for download:
https://7-zip.de/download.html

No I did not

Then install that then you can do it

OK thanks

Oh sorry, I assumed that Winrar already has xD by default on a computer. Under the Winrar installation you can choose different zip formats that you want to "edit". Among others also 7z. Then it should work.