Can a syllabus be adopted and modified? I have seen some few syllabuses online that look very similar. Is it fine to adopt any syllabus or instructors need to have their own syllabus? And do instructors need to get permission from the original syllabus writer or just link and acknowledgement?
In some cases, it could be that the instructors had a template provided by the school.  When I was an instructor at a college, I was required to update a few things on the syllabus, like my name, but I was required to NOT change ANYTHING else.  I had no flexibility (in that one specific way...  I did have a whole lot of flexibility with just about every other way that I ran my particular class, which I know is quite different than what some other instructors experience).  One thing I did have the flexibility to do was to create my own addition to the syllabus, but the college bureaucracy, which determined the official course objectives, also mandated a certain amount of information get presented unaltered.

In that case, I, as the instructor, never bothered to check the copyright of each and every syllabus, because obviously I had the organization's permission to do what the organization absolutely required of me.

This is just one example: The main point being, in some cases, instructors might not be creating their syllabus entirely from scratch.  Surely, the specific details vary from school to school.