Interview required a basic written skills test. Very few people failed it. Basic EMT-B stuff that you studied for in the NREMT (though easier)
After that, you get a followup call to come in for a personal interview with someone in management. Some interviewers are much harsher and more intimidating than others. But if you know which end of the stethoscope goes into your ears, you will be hired.
You must also pass a drug test (even though Marijuana is legal in WA state, AMR's drug policy is nationwide and prohibits marijuana use. Though other prescribed controlled substances such as painkillers and stimulants will not impact your ability to be hired, as long as it's not actually impacting your capacity to function in the job)
After you are offered a job, you will be given a CPAT physical exam, consisting of two minutes of constant compression CPR, walking up and down a flight of stairs while holding a 35lb bar several times, two minutes of stepping up and down the stairs (without weights) and loading and unloading a gurney.