Hi,
To begin with, try resetting the printing system and re-adding the printer. Check whether the operating system offers a suitable printer driver.
Reset the Mac printing system to solve a problem - Apple Support
Add a printer on Mac - Apple Support
There are Linux (for example, Ubuntu) drivers from HP for the Samsung CLP-300.
https://support.hp.com/us-en/drivers/selfservice/swdetails/samsung-clp-300-color-laser-printer-series/19133844/swItemId/fp-194243-2
If you have access to an old (spare) PC with a network card, and if nothing else works, a workaround could possibly be to install (an earlier version of) the free Ubuntu operating system on that machine. You may then want to carry out an experiment with the CLP-300 connected by USB to that PC. The idea is to share the local USB printer on a network. Ubuntu uses CUPS and understands Bonjour. Sharing a printer in Ubuntu can be done via the CUPS (web) interface. A Mac connected to the network ought to be able to see and use the shared printer. The PC wired (by Ethernet) to one of the LAN ports of a Wi-Fi router would allow wireless access.
Yet another way could be to use a virtual machine running an appropriate (earlier) version of Windows under macOS Mojave 10.14 on the Mac. Printer drivers for Windows are available for the CLP-300.
