It looks like they've been around since 1999 in Arizona doing healthcare staffing.
In 2021 they were acquired by Health Advocates Network and operate as a separate division of them. (Press release from 2021 about the acquisition:
https://www.prweb.com/releases/heal...pany_to_work_for_in_arizona/prweb18256693.htm )
They have 175 Google reviews with a 4.6/5 rating. Some of those reviews go back as far as 11 years. (That's a good sign, IMO. Would be more of a red flag to me if all the Google reviews were super recent.)
Better Business Bureau of Scottsdale lists them with 15 reviews at 5/5 stars, and the BBB corroborates that they've been in business for 24 years.
https://www.bbb.org/us/az/scottsdale/profile/employment-agencies/acclivity-healthcare-1126-31003185
I don't have any personal dealings with them - it looks like they might be predominately Arizona-focused. However, I can't see anything that would indicate to me that it is a scam company. Legitimate web sources corroborate them being in business for a long time.