A few things to check.
1. Supported Printer Language. You mention downloading all the Mac drivers. If the C50xx does not have the Postscript kit activated, then you will have to use the UFR2 driver. To check if the PS kit is installed, press the Check Counter button on the C50xx and scroll down a page or two. If installed you will see an entry called PS.
2. Protocol. For both the UFR2 and PS driver, you should use HP Jetdirect-Socket for the Protocol. No queue name is needed, just the IP address and the C50xx driver in the Use menu.
3. Dept ID Management. If you have to enter an ID/PIN in order to make a copy, then Dept ID management is most likely enabled (although there are 3rd party apps that behave in a similar way so you should check with your IT). With the Dept ID Management enabled, if you print to the C50xx without entering a supporting ID/PIN, then you print job will vanish. Reply if this is enabled and I can give you direction on how to configure.
4. Fiery. There is an optional print controller known as an imagePASS-B1 (aka Fiery) available for the C50xx series. If your C50xx has this fitted then you cannot use the Canon PS or UFR2 driver and need to use the imagePASS-B1 driver. To check if the Fiery is being used, open a web browser and enter the IP address of the C50xx. You will either see a login page for the C50xx or the Fiery Webtools page for the imagePASS.