The EPP key (Authorization code) is one of the safeguards against unauthorized transfers of domain name registrations and it protects your rights as a domain owner. The EPP key is required when transferring .com, .net, .org, .biz, .info and .us domain names. It is not possible to initiate a domain name transfer for these domains without an EPP code.
If your domain is registered by SiteGround you can find the EPP key in your Customer's area, My Account, Domain names. Next to the domain you are interested in there will be a button "Manage". Following this link will provide you with all the information about your domain name including the EPP key.
If you are a Rebel Networks reseller, you can find the EPP key in your Reseller Area. Next to the domain you are interested in there will be a button "Manage". Following this link will provide you with all the information about your domain name including the EPP key.
Please note that EPP codes are case sensitive.
If you are having issues with your host/registrar and you cannot obtain your EPP key, you may not be able to manage your domain and transfer it elsewhere. In such cases it may be best to use a new domain name for your website.