Q: iPhone remote for keynote 6.2

You may want to download an earlier version, Install the latest compatible version of an app on an earlier version of iOS or OS X - Apple Support

The Keynote Remote function is built into the Keynote for iOS app, available at the AppStore, to allow an iOS device to remote control Keynote playing on a Mac.

details are here:  Keynote for iOS

You wanted a remote control app for Keynote, the Keynote for iOS app has the dedicated remote control function built into it.

It is a fully functioning version of the Keynote for iOS app.

When installed on your iPhone or iPad, it will control Keynote on the Mac.

I have no difficulty in using Keynote remote in any of our systems, it is reliable and simple to use. Most complaints reported here in this discussion are caused by users not setting up the app correctly.

I completely agree that a free trial would be useful, unfortunately the App Stores policy is not to allow trials of any app they supply.

You could try this alternative, we have it installed on all our iPads to control the Mac, it offers remote control of a number of Mac apps- Quicktime iTunes PowerPoint . As it costs only £0.79 its near enough a free trial:

Rowmote Remote control for Mac