This runs on Qt 5.15. In the Qt Maintenance Tool ensure you have both the Qt Creator and Qt 5.15.0 installed. Qt Open Source edition's online installer can be downloaded here (Note: this requires a Qt account).
Running in debug mode requires OpenSSL 1.1.1 32-bit, which can be directly downloaded from here.
Follow the OpenSSL installation instructions found here once downloaded and installed (from step 3).
Note for anyone who finds this project: this will not work unless you add your own Spotify API token and secret, as I have reset the token this project used.