Welcome to Android Central! Which phone? Does this occur on both wi-fi and mobile data?
Try going to Settings>Apps>All, select Google Play Store, and Clear Cache/Clear Data, then Force Stop. Do the same with Download Manager. Now try again.
DF-SA-01 can also apply to paid apps if there's a problem with your account. The only way out of that one is to go to Google Wallet. It will ask you to submit documents. Upload pictures of the documents. It usually takes 24-48 hours to get the account straightened out.