Custom ROMs cannot legally include Google Play Services or the Play Store due to licensing restrictions. Open GApps is the bridge that transforms your vanilla AOSP ROM into a full-fledged Google-integrated device.
Open GApps is an open-source project that develops and maintains Google Apps packages for custom Android distributions. Unlike proprietary GApps packages, Open GApps offers transparency, regular updates, and a variety of package sizes to fit your storage needs. open gapps android 7.1.2
: Your device will take a moment to set up Google Play services. Why Android 7.1.2? Custom ROMs cannot legally include Google Play Services
For 7.1.2 specifically, several historical issues have been ironed out: Open GApps offers transparency
Match your device's CPU architecture (ARM, ARM64, x86, or x86_64).