Sforzando

With Reaper on Windows if you want to play piano, bass, drums etc you need to install some kind of software synthesizer. Here is a free one called Sforzando (download here) (more info here) that you use to play Soundfonts which include samples different instruments and you play these like a synthesizer.

Some amazing free resources

https://www.flstudiomusic.com/2018/09/free-beat-drmr-virtual-drum-machine-plugin-with-2136-drum-samples-released.html

https://www.kvraudio.com/product/beat-drmr-by-beat

Trap

https://www.flstudiomusic.com/2018/05/newloops-free-trap-kits-loops-one-shots-and-midis.html

https://www.flstudiomusic.com/2017/08/free-dj-architect-sample-pack-vol-1-released-trap-drums-sfx-synths.html

https://www.flstudiomusic.com/2017/03/free-analog-drum-samples-abletunes.html