I am having the same issue, although I am trying to set up my DisplayLink docking station for the first time today.
I have the following Pluggable docking station:
https://www.ebay.com/itm/264830205532
I am using DisplayLink Manager 1.3.0 (Build 56.111)
My computer is a 13" Apple M1 Macbook Pro (2020), running on Big Sur 11.3
I have (2) HP VH420a monitors, both utilizing an HDMI connection
I have hooked everything up, and my second monitor is not being recognized. Pretty big bummer after dropping $172 on my docking station.
Anybody know what I can do to fix this?