Step 1 : Stick it in your PC
Step 2 : Don't do anything else, I swear
Step 3 : Go into osu!
Step 4 : Click options, then go to the keybindings
Step 5 : Click each taiko binding and hit the corresponding sides
Congratulations, you're winner.
If that didn't work, try joy2key.
Otherwise, your drum may be broken, or you can try other USB ports, I dunno. Don't give up! I'd try using it on another game, because it does have the buttons at the bottom, so it could theoretically play some games. That way you can see if its osu! or your computer or the drum.