Open Gapps Project is probably the easiest way to download the latest and correct Google Apps for custom ROMs. A number of different versions of the apps packages are available such as aroma, stock, full, mini, nexus, etc. You can choose a basic or full package to suit your exact needs. All packages should work fine on any custom Android 4.4.x or 5.1.x ROM.

Currently only arm and arm64 platforms are fully supported. x86 platform still misses some apps packages in full and stock package. Also, x86_64 is under development. The latest download can be chosen by platform (arm, arm64, x86, x86_64), Android version (4.4, 50, 5.1) and package variant (aroma, stock, full, mini, micro, nexus, etc). Interested users go Open GApps Project [HERE], download the required Gapps for your ROM and flash it. (source – XDA)