You are installing Agent on a Windows 2003 or Windows 7 machine.
The installer shows the following warning:
The KB940349 update is not installed on this machine. Install this update to avoid disk backup failures
An outdated VSS version is installed on the machine. To guarantee correct backup functioning, we always recommend updating VSS components to the latest available versions.
KB940349 mentioned in the text of error is an update released for Windows Server 2003 back in the day, which was supposed to improve the reliability, scalability, and memory optimization of the Volume Shadow Copy Service (VSS). This update cannot be downloaded separately anymore, as Microsoft Windows Server 2003 is not supported by Microsoft since July 14, 2015.
To resolve the issue, please make sure that all the latest available updates for your operating system are installed, as these should include the mentioned fix as well. After that, proceed with the installation.