There are two variants of the Saffire 6 USB - one is a USB 1.1 device and the other is USB 2.0. To check which variant you have you can reference the serial number on the underside of the unit: if the serial begins "SU" then you have the USB 1.1 variant, it it begins "S2" then you have the USB 2.0 variant.
Saffire 6 USB 1.1 is no longer under development support, meaning we are not able to provide any further updates to support macOS Catalina or future versions of macOS or Windows. Saffire 6 USB 1.1 will continue to function as normal on macOS 10.14 Mojave and below, the latest version of Windows that Saffire 6 USB 1.1 was tested on is Windows 10 build 1809 - you may experience problems with your Saffire 6 USB 1.1 if you update Windows beyond this version.
Saffire 6 USB 2.0 is supported on macOS 10.15 Catalina and Windows 10 build 1903. Please continue to check on the compatibility status of Saffire 6 USB 2.0 before updating to future operating systems.