Why can't I play games on my PS4 on the ext. Move hard drive?

I recently bought an external hard drive because I don't have enough system memory to carry out updates alone. Then when I wanted to move my games, especially Modern Warfare (102GB) to this one, I couldn't. Just like Apex Legends and Fortnite. Why is that and what can I do about it? I have no desire to have these 80 euro in the sand. And is it usual that moving the games (e.g. 50GB) takes around 50 minutes?

You can't just move programs. The operating system would no longer find this and can't be started. If it works on Steam or something like that, see how you can do it.

Could I uninstall the games and reinstall them on the hard drive instead of the system memory?

https://blog.de.playstation.com/2017/03/10/how-to-ps4-spiele-und-apps-auf-eine-externe-festplatte-herunterladen-und-speichern/amp/

Did you do that?

Ps. I'm sorry. Overlook that it's about a PS4. Comment is more for PC.