I'm creating a website on which users can pay with a credit card.  I downloaded the php_payment code from github.  I enter the card info, but when I submit, it always says:

Caught Exception!

Response body:

Null

Response Headers:

Null

I am using the sandbox settings, ID and token.  I've recreated the project a couple times but no luck.  This issue has already been asked here:

 https://www.sellercommunity.com/t5/Questions-How-To/PHP-code-always-ends-with-caught-exception/td-p/...

but the solution doesn't work for me.  I am completely stumped.  Can anybody help me out please??

I'm trying to test on Localhost, os: windows, browser: chrome. I've used the server started from the command line as well as MAMP.