yes you may, and sell your game, as long as I am credited:) See the Usage section:
“You may use some or all of these tracks in your game as long as you credit me, Sara Garrard and/or sonatina.itch.io.
If you make some money with your game or plan to, a donation is appreciated, but not obligatory.”
(You can use the music in games and in promotional material relating to the games eg a trailer on YouTube; you can’t use it in other situations like in a movie etc without asking further permission, and you can’t sell the tracks yourself.)
Thanks! Good luck with your projects.