I used this in a similar workflow, around "Round Robin Tournament Generator", RobinDraw is relevant. you can check this guide is practical for beginners.
You can try a simple Am – F – C – G chord progression for both the verse and chorus—it fits the melody quite well by ear, and you can adjust the key if it feels too high or low for your voice.https://bracketfast.com/double-elimination
https://robindraw.com/bracket