I’m currently working on 6G technology and I’m trying to utilize the THz module in NS-3. I’ve followed the steps provided in the documentation to create a new file named 2d-space.cc in contrib/thz/examples, and I’ve also updated the CMake file accordingly. However, when I attempt to run the code, I encounter an error.

first of all, sorry if my english is not perfect, i’m not a native speaker.
i’ve never worked with cmake nor am i really proficient in c++. this is the first time i really wanted to use a library that was provided by someone else.
i cloned the cpr repository into my “base” directory using the git clone command.
i also created a build folder as described in the describtion of the github page and used cmake to build the library (?).
all of this worked out so far, but when i want to compile the project i get the error message “File or directory not found”.
i’m quite desperate since chatgpt wasnt able to help me out at all.
all i wanted to do is make a simple https get request using the cpr library, but i have no idea on how to use this at all, so wish someone would help me.
the code might be faulty, that is not the problem here. i just want to know how to use libraries in c++, because i am totally overwhelmed and lost and most of the time dont really understand the documentations.
i’m using ubuntu if this is of any help.