Delete everything and start again, as it's hard to determine where you went wrong.
Cobalt's file share (download to PC and move files over to device):
https://mega.nz/#F!lIUWjSSQ!yoLoiNX3PNG3Sef1Fa_fMA
Install and login with 4.3.3.
Install and register with 2.8.
Install Play Store v6 build2.
***Stop here if all you want is Play Store
Install Play Services v11.
Install 4.4.4 (but don't open after)
Install Play Games v5 (if desired).
Install whitelist 1.0.0.6.
***If an app requires Google Play Services, then:
Download app with Cobalt's Play Store (but don't install).
Whitelist unpatched app.
Patch app on PC with Play Services Patcher 1.6 using defaults settings.
Install patched app.