You don't absolutely need a mixer. Your Rybozen wireless mics also has a simple mixer with it. You just have to connect it to powered speakers using the Audio Out jack on the back.

A powered speaker I recommend

https://www.amazon.com/Rockville-RPG15BT-V2-Bluetooth-Additional/dp/B088ZH5CGH

cable to connect Rybozen to speaker

https://www.amazon.com/FosPower-Plated-Stereo-Splitter-Adapter/dp/B00LBK389I?th=1