You must use a recent verison of Chrome or Firefox with adblocking disabled to record voice notes.
At this time, we are unable to support Safari and iPhone due to technology restrictions on Apple's end. We hope they make the necessary changes soon.
Even if it says you are using Chrome, it still has the technical limits of Safari on an iPhone and will not work right now. Same goes for Firefox and other browsers.
Please contact support and we'll be more than happy to help you out.