APKMirror is owned by the team behind Android Police and is the industry standard for safe APK files. All uploads are signed with the original developer signature.
If you are flashing a custom ROM, do not install Account Manager alone. Instead, flash the full Open GApps package for Android 7.1 (nano or pico is fine). download google account manager 7.1.1
The Account Manager will be automatically included. APKMirror is owned by the team behind Android
If you have developer options enabled:
adb install GoogleAccountManager_7.1.1.apk