Why can't I download UE4 source code?

dear experts:
i’m from china, i registered in www.unrealengine.com, and subscribed, and then unsubscribed, because i only want to study within only this month.
but why can’t i download ue4 source code from github? and the github just showed me that"This organization has no public repositories."and nothing more
so help me with downloading, thx

Hi Huangdong,

There is a guide on our wiki for users getting source code from GitHub for the first time. The section I linked to might be what you are missing. You need to add your GitHub account name to your Unreal Engine account. You will then receive an email from GitHub (usually within five minutes) inviting you to join the Epic Games Organization on GitHub. Once you join, you can create a fork of the Engine source code.

Your subscription will remain valid for 30 days from when you initially subscribed. Please let us know if you continue to have any problems after linking your GitHub and Unreal Engine accounts. Also, keep in mind that you will be removed from the Epic Games Organization on GitHub after your subscription period expires. A short while after that, GitHub will remove your fork of the Engine source code from their servers, so make sure you have local copy of the source code on your computer before that happens.