From an External Perspective:
Zebra ZP450 UPS (ZPL) Printers are designed and sold exclusively for use with UPS Shipping Applications only.

These Solutions are Windows-Based and there is no Non-Windows Solutions that Zebra Support portal provides for alternative use-cases, such as MacOS X, or for Linux.  ( Depending on the OS you are running on the rPi, your milage may vary on what you can try to look at for the USB interface, but Zebra Support cannot assist you with that, and that is not a Zebra supported option )

As well this document discusses the older printer and this newer printer, which is highly aligned to UPS label printing operations.

https://supportcommunity.zebra.com/s/article/UPS-LP2844-and-UPS-ZP450-Printer-Setup-and-Troubleshooting?language=en_US 

The Zebra ZP450 printer can be used with a Raspberry Pi 4 and Python. The ZP450 typically connects via USB or Serial (RS-232). The Raspberry Pi 4 can support both types of connections. Ensure you have the necessary drivers installed on your Raspberry Pi for the ZP450. You can usually find these in the CUPS printing system. Check out https://supportcommunity.zebra.com/s/article/UPS-LP2844-and-slice master-UPS-ZP450-Printer-Setup-and-Troubleshooting this news for more information.