I am currently in the process of getting my HND (Higher Natonal Diploma) notarised/legalised and then authenticated. If your university or college isn’t on the list of “recognised institutions” then I believe that you must go through this process.
Due to me having a 2 year college course (UK version of an associate’s degree) along with a TEFL, this is the only way that I can work legally in Taiwan.
I am moving back to Taiwan in March next year (from England) so I am getting all of my ducks in a row now.
I have already had the diploma notarised, it is currently with the FCO in the UK getting legalised, the final step will involved me sending it to the Taiwan representative office in London to be authenticated what an arduous task.
I hope this helps, there are a few threads on here that cover this topic, some more in-depth than this post.