DisplayLink is warning of significant macOS issues as shown here.
Thee DocKtor recommends that macOS users request support from Apple for these issues so that they have full awareness of the issue(s) you are experiencing.
As shown, some functionality is available with the DisplayLink USB Graphics Software for OS X and macOS 4.3 beta 3 release. However, Thee DocKtor has not validated this release for use on Targus Universal Docking Stations with any version of the macOS or OS X.
Thee DocKtor is recommending that macOS users stay on macOS version 10.13.3 and use DisplayLink release 4.1 until Apple releases an update to fix these issues.
Status at DisplayLink as of April 13th, 2018
Installing macOS release 10.13.4 will cause DisplayLink connected displays to go blank after the OS upgrade when using our driver v4.1. (Functionality such as Ethernet and/or audio, where implemented, is unaffected.) Extended display support continues to work as expected in mac OS 10.13.3 and that is why we recommend you stay on 10.13.3 for now, if you have not already upgraded.
For users that have already upgraded to 10.13.4, we have released 4.3 Beta 2, which enables cloning of the native display on DisplayLink connected screens. We do not regard this as a long-term solution and will continue to pursue any paths to restore extended display support on macOS. The 4.3 Beta 2 release can be downloaded from http://www.displaylink.com/downloads/file?id=1131.
As we use our own technology every day, we truly understand that this loss of functionality on the OS upgrade is very frustrating. We are continuing to explore with Apple routes to a solution. In the meantime, our teams are working hard analysing potential workarounds, which could enable some level of extended desktop functionality in 10.13.4. Finding a solution to this issue continues to have the highest priority within DisplayLink, and we are providing any support we can to our mac teams.
Unfortunately, we are not yet able to give a date for delivering a solution but we will continue to update you on this thread as soon as we have further information to share. You can also use the contact form to create a ticket with your email address and ask to be added to an email list dedicated to this issue.
We thank you for your patience as we work this problem.