what PEX fittings can I use with a Zurn PEX QickClamp Crimp Rings?
PEX labeled fittings are uniform (essentially). You can use any pex labeled fitting with any pex labeled tubing and any pex labeled crimp ring, provided they are all labeled for the same size tubing and the manufacturers literature shows as astm compliant. For ordinary residential remodeling you don't need to be concerned with pressure ratings of the assembly.
Note that PEX labeled components are for use with potable water only, unless otherwise noted in the manufacturers literature (I don't know of any exceptions but they may be out there).