Hi. I wrote a plugin for payment integration in easy digital downloads for First Atlantic Commerce. This was done recently so I am very familiar with the process, and in fact had used the same link you provided in your description as my starting point. I can work on this gateway for you and have already started reviewing the G2A documentation.
I have a total of 10+ years in the IT Industry including two Microsoft Professional Certificates and have been working with wordpress and other cms platforms for the past few years. Also, please take a quick look at my profile/feedback and you'll notice I'm a 100% trusted freelancer, a reputation built from perfect accuracy, attention to detail, excellent efficiency and great communication. I strongly believe I'm the perfect candidate for your job and you can be confident knowing you've hired a professional who delivers on-time.
Thank you for reading my proposal and I look forward to hearing back from you toward the start of a healthy working relationship. Kind Regards, Kenny.