Many legacy enterprise systems were built on the Quartz 1.x branch. Quartz 1.6.6 is often cited as a mandatory prerequisite for:

Finding official downloads for such an old version can be difficult as modern repositories prioritize the 2.x branch. News archive - Quartz.NET

Specifically for the Electronic Messaging Service (EMS) and FGL Application setups.

The core library file to be placed in the application’s classpath or specific plugin directories, such as {INSTALLER_DIR}\Library\plugin-quartz .

The .NET port of Quartz, version 1.0.2, corresponds directly to the features and logic of the Java Quartz 1.6.6 release. Package Contents of quartz-1.6.6.zip The distribution package typically includes: