Hi, my name is Adam and I am a UK business and IT university graduate. I am willing and more than able to help you meet your requirements within the next few hours. I am looking to build a reputation within freelancer and a project such as yours would be a great start. As such I offer my services at a low price.
If you feel my IT background is more than adequate, then feel free to message me to discuss further. The creation of a subdomain should take in a reality less than an hour but this does depend on circumstance. I presume with siteground you are using cpanel and a such this would be a quick job for me.
I look forward to hearing from you,
Regards,
Adam Goforth