Either it’s getting lost in translation, or there is deliberate obfuscation going on.
There is a misconception that anyone who is not a full-time employee/worker is not an employee/worker, period. This is false. What matters is the type of contractual relationship, not the hours of work. Also, your residency status is irrelevant in determining whether or not labor insurance is compulsory for you.
We were just discussing this in another thread btw.
You can ask the Bureau of Labor Insurance about your contract, but in my experience you’re likely to get better service talking to your local labor department.