Re: how can i fix error code rpc:s-7AEC
Welcome to Android Central! Did the device come with Google Play Store preinstalled, or did you have to manually install it? Have you been able to successfully install other apps from Google Play?
Go to Settings>Apps>All, select Google Play Store, and Clear Cache/Clear Data, then Force Stop. Do the same for Download Manager.
If that doesn't help, go to Settings>Accounts, and remove your Google account completely, then add it back again.
Also, open Google Play Store, swipe in from the left, tap My Account, and make sure you have a valid form of payment associated with your account.