I'm not sure if this job is legit or not (in person)

I recently applied for a job at a consulting agency, and I feel an off feeling about it, it seems too good to be true. Here’s a timeline of what happened:

• Tuesday: Applied for the job.

• Wednesday: Got a call and scheduled an interview.

• Thursday: Had my first interview.

• Friday: Completed my second and third interviews and received a job offer.

On their Indeed they didn’t include how much I would be paid, and when I was offered the job, they didn’t put in writing how, or how much I would get paid. There are other reasons why I’m iffy about it too. They claim I can upgrade my role every 1-2 months and potentially make six figures in a year. I didn’t receive a formal job offer letter. Instead, they sent a congratulations email and a request for a background check. This background check was from Sterling and I’ve heard bad things about it, not to mention neither the agency nor Sterling is registered with the Better Business Beuro (BBB). They mentioned in the interview that the pay is weekly, with a base pay of $ 400 and potential commissions between $600 and $2,000 on average but like I said, I’ve received nothing in writing to second that fact. I’ve looked on their website and the employees tend to travel a lot and have fun together and the environment looks like a work-hard play-hard type of place which isn’t bad on its own but coupled with everything else raises some red flags They say that I must do the background check before I can technically work but because this job seems so suspicious I’ve held back for now. My first day is on Tuesday and I’ve been advised to hold back on the background check and ask for written proof of my wages on the day of training. This is my first corporate job and I wanna make sure that it’s safe for me to work.

Also this is the email that I received from them. Details were changed to protect my privacy.

Dear [New Hire],

We are thrilled to welcome you to the __________ team! You were chosen because we believe you have the qualities needed to excel with us.

In your role at ___________, you will be encouraged to broaden your horizons and tackle new challenges daily. Our training programs will provide you with the necessary coaching, and our open-door policy means we are always available to discuss your progress. Congratulations on joining ___________!

You will receive a separate email with a link for your background check. Please note that failing to complete this step may delay your hiring process. This email will come from a “no-reply” address with the subject line: “On behalf _______, Inc: Ensure there are no gaps in your address history. Providing continuous living addresses from your birth month and year up to the present day is essential.