What soundcard did you get?
Post a link.

That looks good. From what I can tell it has mic preamps and lin-in jacks, as well as midi i/o. As long as you get the rite cables you'll be able to get your keyboard hooked up to it. You just need y cable, which has a 3.5 mm male on one end and 2 1/4'' trs males on the other, which will take the stereo audio of your keyboard.
I think the keyboard has multi track capabilities, meaning multiple trs outs on the back, but I'm not sure.
Then you plug 2 midi cables, one from midi-out on your keyboard to midi in on your interface, then from midi in on your keyboard to midi out on your interface. Then you'll be set.
I think that usb mic you have may become an issue because with Reaper you can only use one audio source. Meaning you can't use your usb mic to record vocals and your interface to record/sequence your keyboard at the same time, unless there's some kind of bypass feature I'm not aware of.
If you get a mic for your interface, I'm going to suggest to you the AudioTechnica AT-2035. It's a really good entry level mic at $150. I'm using it rite now.
Another thing with audio interfaces that annoy me a little bit is their software, at least with my focusrite, is a bit inaccessible. Which once again gives me another reason why real, actual hardware with all the buttons, knobs, faders, pots, etc, is a lot better. But I digress. Hopefully that won't be an issue for you.

you might find many sounds for all kinds of stuff, some even gm based so you can just load and change presets here
https://musical-artifacts.com/

@31, Thanks for the link .
I have some questions: How do you play sounfonts on mixcraft? I'm using mixcraft because there's a little delay when I played some vsts from my keyboard to reaper and my pc don't support asio.
And is there daw's that mor accessible than mixcraft other than reaper?