Aliplugin error: 'Could not connect to AliExpress'

What could cause the error 'Could not connect to AliExpress' when trying to import products into my shop? I have an AliExpress API key (5 digits) which I entered, I also entered my affiliate id.

What else is required to get the Aliplugin to import products?

Also, Aliplugin asks for an 'APP Key' but Aliexpress gives me an 'API Key'. Are those the same, or not?