Use it with what you usually use
The introduction to the document says:
This document is the first in a series of Unearthed Arcana articles that present material designed for the Player’s Handbook coming out in 2024
The material is intended to only replace material in the PHB. Normally you would combine the PHB with whatever other books you use: Monster Manual, Dungeon Master's Guide, optionally others.
The One D&D announcement stated:
The One D&D rules will be backwards compatible, allowing you to continue enjoying the adventures and supplements you play with today. Our goal for One D&D is to evolve the game in a way that reflects what players have told us they love and that makes it as versatile as them.
So the goal is to upgrade your experience without invalidating existing investments into adventures and supplements you already made. Hence, it should be possible to use it together with them.
You can expect changes to also come to the DMG and MM, but as they are not circulated yet, you have no way to use those, and in the interim can only use what you have. Once these come out, you should of course use those over the current DMG and MM rules, where they override them.