X64 and x86 for android greyed out ask for github source

Where to download 4.16 source??when ever i try to download page says 404 error.link is given below
So i sign in both unreal and github website and also register username
But 404 error
Please is their any way to do that stuff on exiting version of editor.
I try to add lines in project/config/engine.ini something like that and tick appears in setting but build fails for android.
So please suggest.
And sorry for my bad english.