This issue is explained in the GenP Guides Troubleshoot Section:
FAILED / RETRY / ERROR CODE 304
If you encounter any of the above errors when attempting to install an app, follow these steps:
Ensure that you are logged in as an Administrator and that CC is running with Administrator privileges.
Go Menu > File > Quit Creative Cloud, then reopen CC as Administrator and attempt the installation again
Alternatively, restart your device, reopen CC as Administrator, and try installing the app again.
Check the Cloud Activity icon, if it has a red dot, this may indicate the cause of your error.
Ensure that you have enough disk space to install the required app. This means not only meeting the minimum system requirements but also allowing for additional disk space that temporary installation files will use, as well as for stored app data which Adobe places on your main C: drive regardless of the chosen installation location.
Confirm that you have the latest version of Visual C++ installed, both x86 and x64 versions must be installed. If you already have the latest versions, repair your existing installs and restart your device when prompted. Visual C++
If the issue persists, use the CC App Uninstaller Tool to either repair or uninstall and reinstall CC. CC App Uninstaller Tool
You don’t need to uninstall any apps, ignore that initial part of Adobe’s instructions. Instead, open the tool, select “Repair” and let it run, then restart your device and repatch CC with GenP.
If the error persists, use the Uninstall option instead. Let the process complete, restart your device, reinstall CC, and repatch CC with GenP.
This issue is explained in the GenP Guides Troubleshoot Section:
FAILED / RETRY / ERROR CODE 304
If you encounter any of the above errors when attempting to install an app, follow these steps:
Ensure that you are logged in as an Administrator and that CC is running with Administrator privileges.
Go Menu > File > Quit Creative Cloud, then reopen CC as Administrator and attempt the installation again
Alternatively, restart your device, reopen CC as Administrator, and try installing the app again.
Check the Cloud Activity icon, if it has a red dot, this may indicate the cause of your error.
Ensure that you have enough disk space to install the required app. This means not only meeting the minimum system requirements but also allowing for additional disk space that temporary installation files will use, as well as for stored app data which Adobe places on your main C: drive regardless of the chosen installation location.
Confirm that you have the latest version of Visual C++ installed, both x86 and x64 versions must be installed. If you already have the latest versions, repair your existing installs and restart your device when prompted. Visual C++
If the issue persists, use the CC App Uninstaller Tool to either repair or uninstall and reinstall CC. CC App Uninstaller Tool
You don’t need to uninstall any apps, ignore that initial part of Adobe’s instructions. Instead, open the tool, select “Repair” and let it run, then restart your device and repatch CC with GenP.
If the error persists, use the Uninstall option instead. Let the process complete, restart your device, reinstall CC, and repatch CC with GenP.