Website music playable on iOS?
HTML5 and Flash are not the same thing.

Flash is a proprietary browser plugin. Flash is not available on iOS devices, full stop, and support outside of iOS devices is spotty at best.

HTML5 audio playback is supported by mobile Safari as of v6.0 (which corresponds to iOS 6 that came out in 2012) according to this page, as well as Google Chrome which runs on Android devices. Between those two, you are covering 95+% of the market for mobile devices.

Presuming you are targeting mobile devices, HTML5 audio would be the best solution. If you are also targeting desktops, HTML5 with a Flash Player fallback would probably be worthwhile.