I tried to download the free species, though when I go to create eggs it says that the sprites aren't found...

Any help?

Btw, this is for C3

Have you installed the Creatures Remastered Patch? Without it, Creatures Exodus does not install new breeds, agents, and updates to the correct location. This is usually the easiest way to get the breeds working, although I believe you will need to reinstall them. Hopefully this solves the problem! If not, feel free to post any other information, such as the exact breeds. Good luck!

I hope this does not sound too stupid, but where do I put the patch when installing it?

The .zip file includes a short Readme, but you should extract the contents into a folder and then run the .exe. There is no specific location to place it. Since it's a .exe program, it will run itself, patch any game(s) you have installed, and then you should be all set!