The TBT-6950PD docking station can drive up to a maximum of four external displays, using a combination of two different technologies.
The dock provides two HDMI video outputs driven by DisplayLink technology. DisplayLink technology is compatible with almost all modern Windows and macOS computers. The result is that both HDMI outputs will function so long as the required DisplayLink software is installed on the host computer.
The dock also provides three 'downstream' Thunderbolt ports, driven by the Intel Goshen Ridge Thunderbolt chipset. The capability of these ports in regard to video output is ultimately determined by the capabilities of the host computer.
When using a host computer that supports two external displays via Thunderbolt, it will be possible to connect up to two additional displays to the dock's downstream Thunderbolt ports by using either USB Type-C cables or USB Type-C to video adapters.
When using a host computer that supports one external display via Thunderbolt or USB Type-C, it will be possible to connect one additional display to the dock's downstream Thunderbolt ports by using either a USB Type-C cable or a USB Type-C to video adapter.
All of this together means that when used with a host computer that supports two external displays via Thunderbolt, it is possible to use a total of four external displays via the TBT-6950PD.
When used with a host computer that supports only one external display via Thunderbolt or USB Type-C, it will be possible to use a total of three external displays via the TBT-6950PD.
For reference:
Thunderbolt 4 host system
When the TBT-6950PD is connected to a computer with a Thunderbolt 4 port, the maximum number of displays that can be connected to the docking station is four.
Thunderbolt 3 host system
Manufacturers have discretion when designing their Thunderbolt 3 systems in regard to how many displays are supported via a single Thunderbolt 3 port. Some Thunderbolt 3 systems support two displays, while other Thunderbolt 3 systems will only support one display.
Thunderbolt 3 systems that support two external displays via their Thunderbolt 3 port will be able to support a maximum of four external displays via the TBT-6950PD.
Thunderbolt 3 systems that support one external display via their Thunderbolt 3 port will be able to support a maximum of three external displays via the TBT-6950PD.
USB Type-C host system
Host systems with only a USB Type-C port will be limited to a maximum of three external displays.