Where did you download the DisplayLink drivers from?
You need to check whether the kernel modules have been built successfully.
You can check with either sudo akmods or sudo dkms status.
If your system has Secure Boot enabled, then you also need to enroll the MOK key first, otherwise the kernel will refuse to load the kernel module.
A quick test would be to disable secure boot in UEFI/BIOS and boot Fedora and see if the drivers are loaded and work.
mokutil --sb-state will tell you if secure boot is enabled.