Error when running installer .exe or .msi
This installation package could not be opened.
contact the application vender to verify that this is a
valid Windows installer package
A firewall or company's permissions policies setup will not allow to download any executable and it will timeout before finishing download resulting in creating smaller, corrupted file that is not recognized by Windows resulting in incomplete install issuing above error.
Verify the size of the file that is matching the one that is shown on the download page, if not then please use different method of transfer file.
Usually Webex Transfer File option from the engineer's machine or ftp method works in most of cases.