The VT2900 charges via USB-C Power Delivery, to PC2 with the included power supply, verify that your host system supports this feature. To charge PC1 an additional USB-C Power adapter is required.
If you have both connected to USB-C and neither or only one laptop is charging even with both power supply's connected, make sure that your laptop supports charging over USB-C and does not require more than the dock is able to provide (100W via USB-c).