Are you prompted to enter a serial number or sign in with your Adobe ID when you start Acrobat Pro or Acrobat Standard? There are several reasons why you may be getting this prompt:
The method used to purchase your product determines your launch experience:
The Acrobat continuous and classic versions each use a different installer. If you have installed the wrong version, it's necessary to uninstall the incorrect version before installing the correct version of Acrobat. If you receive a serial number prompt or sign in unexpectedly on launch, you must follow this process to install the correct version of the software.
Important: The trial version uses the classic installer. Continuous customers must uninstall the trial version and reinstall using the subscription installer.
To install the Acrobat as part of the Creative Cloud, refer to the Creative Cloud download, install, and update page.
Volume license customers
Volume license software is provided to the IT or packaging department. Contact your IT or packaging department for information on accessing the Acrobat installation. The information below is for the IT or packaging department.
The classic version is referred to as the perpetual version in previous releases. Access this installer on the Licensing Website.
Access the installer for the subscription installer on the Admin Console.
The serial number prompt may be occurring because your computer is having trouble connecting to Adobe's activation servers. Try working through the solutions in the "Troubleshoot connectivity issues" section in Sign in, activation, or connection errors | Document Cloud, CC, CS6, CS5.5.
Managing a network? See the licensing information in Adobe Creative Cloud Service Access Documentation for IT.
Logging out and logging back in to Acrobat resets your account information.