I'm trying to get the free version of your plugin to work. I've entered the shortcode with the twitter widget ID in place but I get the error message:
The connection to twitter has returned an error. Please try again later.
Of course, I have checked my code and as you can see on this test site, the twitter widget ID I have is working fine in the twitter native timeline embed and also in the Jetpack plugin: http://timbaggaley.co.uk/sketch/
I particularly liked your feature of showing only the tweets of the last seven days, I realise I will need the Pro version to get this feature back but as I'm sure you will understand, I need to see the free version working again before I buy.