It's my 1st time trying to download a custom song and i followed the video from stellarfirefly. I don't have the smashing pumkins dlc so i downloaded the rocksmith toolkit but when i was searching for the DLC that i bought (through glass by stone sour) i couldn't find it. Is there any way i can play the custom song without buying another DLC that i compatible with RC toolkit?

I moved the topic to the appropriate section

 

About the topic itself you can check in the toolkit folder, there should be an appID something .xml where you can add the ID of the DLC that you own to be able to use it in the toolkit.

 

But i would strongly suggest you buy Cherub Rock by the smashing pumpkin as any CDLC here use that ID so that would save you a lot of time for a 3$ DLC.