Intro
DisplayLink itself is a free software, but the docking station that supports this software is not cheap (around $100). After using it for a year, I found that it is not a good Mac multi-screen tool.
Details
My method of use is to connect two screens and work with my Mac closed, which is the most basic way of multi-screen work.
At the beginning, a problem arose: if I don't connect the power cord, DisplayLink will stop working when the Mac is closed, and I have to connect the power cord in order to use it with the Mac closed.
During use, DisplayLink's performance is also unstable. For example, after sleep, the software may stop working and I have to manually open the Mac and restart the software to continue using it with the Mac closed. Sometimes, I even need to open the task manager to force a restart, which is very inconvenient.
Discussion
Mac OS's native external multi-screen functionality has many limitations, possibly due to the closed-loop business model's protection of the desktop product line. But no matter what, it is still a bad design and experience. I hope that in the future, there will be better and more stable solutions.