What is your occupation: Quality Engineer

Attached is the skill assessment I took (TSS Skills Assessment & Competency-Based Virtual Interview {Manual format}), which I completed and submitted for about two weeks before I was sent the offer letter.
The offer was actually advertised on GUINNESS PLC Australia Annex Careers & Latest Job Vacancies.

Does anyone stays in Melbourne?, I'd like if you can help confirm the existence of GUINNESS PLC Australia Annex in the address provided Guinness Level 22 #120 Spencer Street | Melbourne | Victoria | VIC 3000 | Australia.

I have also attached some of the documents out of the ones I have here with me.
@iceberg54, can I private chat you?

Hello @FBS/Everyone,

I need help in confirming the genuinity of the job offer, visa application process and documents sent down by my Australian employer.

I got a job offer from Guinness Australia, Guinness Level 22 #120 Spencer Street | Melbourne | Victoria | VIC 3000 | Australia | and was asked to contact assigned DFAT Case officer who requested me to make a payment of $489 for the enhanced GTE Regional Express Clearance/TSS Subclass 482 Work permit Authorization.

I was about to proceed to make payment but needed to be sure I am doing the right thing and not being scammed.

I would love to share some of the forms/documents so as to help confirm.