Cobalt Strike's Payload Generator outputs sourcecode and artifacts to stage a Cobalt Strike listener onto a host. Think of this as the Cobalt Strike version of msfvenom.

To generate a payload, go to Attacks -> Packages -> Payload Generator.

Set the Listener option to the Cobalt Strike listener you would like to output a payload for.

Use Output to choose what type of output you would like. Most options give you shellcode formatted as a byte array for that language. There are a few options that give you something you can immediately use though:

Check the Use x64 payload box to generate an x64 stager for the selected listener.