Contract interview - no idea what to expect

Got an interview for @Amazon User Experience Designer II through a contracting agency. The contract recruiter is clueless. He sent me slots for next day pressuring me to take it before having any idea what to prepare, who I’m talking to, or even how long the interview will be. over the phone then told me it would be 45 min behavioral 1:1 with the HM. I said, alright, if it's just behavioral I'll do tomorrow. The HM name he gave me was an SDE II. A few minutes later, when i got confirmation, i find its with 6 people on the call for a 90 minute interview. Recruiter says that they're "expediting" the process. I’ve found that getting any clarity from him regarding the process is not going to be possible. Frustrations aside, can somebody please help shed some light on what to expect tomorrow? Is this going to include a design challenge? Prepared portfolio/case study review? How should I prepare? does the contract interview process differ from full-time?