Can you update your repo with the latest version of Music Box 0.2.1No it's not available on Fusion Add-on Installer. Alternatively you could install my Repo via Fusion as I host Techdealer's Repo/Music Box on it as well.
Follow steps in this guide to install my repo but use the 'Alternative Method' in step 12 instead - https://www.tvaddons.co/fusion-installer-kodi/
Your repo has a older version of Music Box 0.1.5
https://git.io/vMVxL Music Box 0.2.1 zip