Since FM24 don't have the licensing to use some names like Manchester United. They also don't have the rights for the German national team and a few other teams, that's why they are missing real players.

This quick step to step guide on how to fix this in FM24. By following the guide all the made up names will be replaced with the real club and competition names and you will get players in national teams like Germany.

This short 4 min 50 seconds video will show you what files on your computer (PC and Mac, Steam, GamePass, Stem Deck and Epic Games) you will need to replace:

You'll find the files you need here:
https://sortitoutsi.net/content/63651/fm2024-licensing-and-real-name-fix-file-beta-version-not-released-yet