I sent you '24R1' links. You can go to your release's help page (click on the question mark symbol on the top right corner in your Fluent UI) and find the information on RGP files in user and 'beta' manual.
NIST lookup table cannot be used for phase change simulations, it only supports single phase and super critical regime problems. You need RGP table files if you need refprop subcritical properties for multi phase simulations.
Another option is to use your own temperature dependent thermophysical (polynomial) and saturation (pt-sat) properties. However, I cannot comment much on smoothness of the runs as it is a case specific trait..
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