The Avnet team at this time does not have any plans to update this reference design to 2018.3.
The process to do so is quite significant. My suggestion would be to revert back your Vivado to an earlier release that is compatible with the available reference design.
The dilemma of software is updating it. Too much out there and not enough time.
Does anyone have a working Vivado 2018.3 Pmod TDNext TD114 Camera project they are willing to share?
The posted reference designs and demos will no longer work with Vivado 2018.3 One of the video IPs is locked and says it's no longer available or upgradable.