Well, I was confused because the Instant Flanger Mk II installer doesn't prompt you about licensing – what you are seeing is the activation window when your DAW is trying to scan the plugin/when you try to launch the plugin.

I just looked at your iLok account, and there is no Instant Flanger Mk II trial license there. You need to request one from here to have a trial license deposited in your account: https://www.eventideaudio.com/plugin_demo?product=Instant%20Flanger%20Mk%20II.