Is Arbolus a scam?

Yes and no. I have been contacted by 3, thrice each. Got paid once

1. Money- triple what they offer, and settle for double
2. They'll ask you for a write up to a set of questions. The answers to it will itself cover what they want to no, and they'll end up not making the phone interview, hence you won't get paid. So i give them just a 1 liner, along with a "check my LinkedIn profile, I am an expert on this" Basically don't spend too much of your time and energy on these ppl
3. Be clear on what you DON'T know. On my call the interviewer said "but you said you know this to the screening person". I politely. replied that I know a gist of how something will work, and i cannot give specific answers to a moving number question
4. Remember to never share non-public or confidential information