Pantone Matching System is the standard for printing when you need an exact color to match every time it prints. Until the update of Adobe Creative Cloud 2023, Pantone (PMS) had included all of their color books within each application.
Pantone changed their business model and now requires you to buy and subscribe to its Pantone Connect plugin to get all the colors. So, not only do you get all the PMS inks, but you also get all of the colors Pantone has created and will create in the future. There are currently 15,000+ colors to use in your designs.
If you haven’t subscribed and installed Pantone Connect, there can be some issues when you open some files. For example, some users report that some Photoshop files created before the update now show PMS colors as black in the file, creating many problems.
Here is the link to subscribe to Pantone Connect https://connect.pantone.com
Pantone Connect is currently $59.99 / year or $7.99 a month as of this writing. There is also a 7-day free trial.
Here is a great article from CreativePro.com that explains the issue further.