How do I send/request resources from the AI ally?

You can ask, but only indirectly! The AI actually sends resources when you have 0, or 1-2 (for resources), 0-999 for gold. If you're playing in an alliance with the AI, don't be stingy and send it 2-5 resources – it will return much more to you. P.S. Of course, you need to understand when this is actually possible!