There are several requirements for the plugin: openSSL and soap need to be activated on your server. If that's not the case, you should ask your hosting company.
The URL of the fedex server is the wsbeta one:
	wsbeta.fedex.com:443/web-services/rate
REplacing it to this one in the file plugins/hikashopshipping/fedexlibrary/RateServiceV10.wsdl made it work for me:
	gateway.fedex.com/web-services/
It would be nice to add an error message when there is a problem:
if($response->HighestSeverity == "ERROR") {
 $app =& JFactory::getApplication();
 $app->enqueueMessage('Fedex Error: '.$response->Notifications->Code.' '.$response->Notifications->Message);
}
Before the line:
if($response->HighestSeverity == "SUCCESS")
in the file plugins/hikashopshipping/fedex.php
The Zone option of the plugin should contain the country of origin as that's what is used (normally that field is for zone restrictions). So, before the code:
					if(!empty($rate->shipping_params->methodsList)){
						$rate->shipping_params->methods=unserialize($rate->shipping_params->methodsList);
					}You should add this code:
if(empty($rate->shipping_zone_namekey)){
 $messages['no_zone_configured'] = 'No country configured in the FedEx shipping plugin Zone option';
 return true;
}in the plugin main file so that it displays an error message if no country is specified.
Then I got that error:
Code	701
Message	Packaging type missing or invalid 
Although I had selected the FEXED_BOX method so I changed it to YOUR_PACKAGING
Then, I had the error:
Code	522
Message	Destination country code missing or invalid
Although My address  was this:
Recipient	
	array(
	Contact	
		array(
		PersonName	Mr paul xxxxxxx
		CompanyName	NULL
		PhoneNumber	xxxxxxxxx
		)
	Address	
	array
	StreetLines	
		array(
		0	xx xxxxx xxxxxxx
	)
	City	villeurbanne
	StateOrProvinceCode	69
	PostalCode	69100
	CountryCode	FR
	Residential	TRUE
)
which sounds valid to me unless FR is not for France in the Fedex API which I don't know. So I was stuck here. Would you have more information on that ?