Edinburgh University Informatics vs Colgate University Physics/Computer Science?

From my understanding, isn’t the typical pathway this. Bachelors + Masters + pHD?
The highlighted quote indicates that the OPT (the 24-month internship) takes the place of the masters?

Here is my question on OPT. After finishing a bachelors in CS, I would have do enrol in the OPT program THEN masters if I were to go to the US right? Or would I extend my visa (if I stay in the US) and complete my masters THEN OPT?