@C_Reider Hello, It means either that Pd cannot find them, or that they are nowhere to be found.
If Pd cannot find them (and you can!) then you will need to use the "edit, preferences, path" window to tell Pd where they are by adding the path to the folder that they are in....(something/something/something/etc.).
If they do not exist on your computer then you are going to have to install "externals" for Pd. You will find a lot of information on this forum about how to do that.......
If you don't succeed then you can download an older (discontinued but fully functioning) version of Pd here....... http://puredata.info/downloads/pd-extended ...which will get you up and running until you can figure it out.
However, installing an external package should be as simple as choosing one, putting it in a folder, and using the edit, preferences, startup window to get it loaded when you start Pd...... unless you have to compile it first for your OS....
David.