You don’t have to do any of that for SU2 5.0.0. They have a binary version and i gave an one line command which would install directly. Did you not notice that ?
Please read the article in full in future before asking a question. Just open a new terminal and type this command.
wget https://goo.gl/pEBKKb -O su2_serial_v50.py && python su2_serial_v50.py
Just copy the above bold line completely and paste it in your terminal, it will automatically install.