After flashing a custom ROM like CyanogenMod, you will also need to flash Gapps package (the default Google apps) to get full access to the Play store. Finding a suitable Gapps package for your device’s architecture and updating Gapps when a new update is available is a real problem. The ‘Open GApps’ app solves these problems by helping you find and update correct Gapps package on your custom ROM.
The OpenGApps website is the best source for GApps package for your custom ROMs. However, before downloading the package, you need to select your device’s architecture (ARM, ARM64, x86, x86_64), Android OS version and Gapps variant (full, mini, micro, nano, pico), which is a real pain for most users. The ‘Open GApps’ app helps you in that.
The ‘Open GApps’ app detects your phone’s architecture, DPI, OS version. Also, it can automatically flash Gapps package on your device via TWRP custom recovery, if you chooses to grant root access to the app. All these will really simplify your task.
For your information, Google apps such as the Play store are licensed by Google and are not permitted to be distributed as part of custom ROMs like CyanogenMod. However, you can download a GApps package and install it from within TWRP recovery, for Google functionality.
Open GApps is a free download on Play store, which will really help custom ROM fans to flash correct Gapps package (Google apps) on their device. Interested users go to Play store here and download the app (Source).