throwaway1011_1's journey

I recently received a job offer from a small marketing agency with about 30 employees. I went through three rounds of Zoom interviews with the hiring manager, another manager, and the CEO. I did my due diligence by checking their LinkedIn profiles and the company's website, and everything seemed legitimate. The hiring manager handled all the communication and there wasn't an official offer letter; just an email welcoming me to the team with details about the role and pay. I’ll be starting as a contractor before transitioning to a full-time role, and I was sent a W9 form to fill out. Initially, I didn't think anything was off until I received an onboarding email today that included instructions on how to get paid. They mentioned I need to send an invoice to their finance email twice a month, detailing the due date, payment address, total amount due, and hours worked. What raised my eyebrows was that they don’t offer ACH payments and instead suggested using Zelle or Venmo for payment. I’ve never encountered a company that pays this way, and I'm starting to wonder if I'm being scammed. Is this common for contractors, or should I be concerned about potential issues when filing taxes?