Thank you so much for reaching out to us, I am sorry to hear that you ran into this little snag, but I would be more than happy to assist.
While we do not support this product on Linux/Ubuntu, we do understand that some users will attempt to utilize the driver that is released by DisplayLink in order to utilize them. Currently, there are no alternate open source drivers that are compatible in 18.04, and DisplayLink only has versions released for 17.04.
I wish there was more that can be done, but we do not develop or product the drivers for our DisplayLink drivers, but it may be beneficial to reach out to DisplayLink directly in order to see if they have any alternative solutions or additional information.
I hope this information helps, but please let me know if you have any additional questions or concerns and I would be more than happy to assist.
Thank you for your patience,
Product Owner & Technical Support