Error 42 occurs because the installer was denied access to a necessary file or folder. This error commonly occurs when Windows cannot validate the digital certificates included with the installation files.
You can find information on how to fix problems updating digital certificates at https://helpx.adobe.com/creative-cloud/kb/Error-code-42-or-72-when-installing-or-updating-Creative-C....
If you have an individual Creative Cloud membership and continue to encounter Error 42, then please download the Creative Cloud desktop app using the Alternative downloads method from https://helpx.adobe.com/download-install/kb/creative-cloud-desktop-app-download.html. Once the installation files arrive, you can execute the installer, and the updated certificates will be added to the computer as part of the installation process.
If you have a Creative Cloud for Team or Enterprise membership, or an organization manages the computer, please get in touch with the organization's Creative Cloud plan administrator for assistance. They can remove any restrictions preventing the certificate validation process from completing successfully.