If i enter the url directly in browser it shows me the rooms available for the checkin that i've put in the link.
But if i run the php script on server the checkin and checkout take no effect, so the website ask me for the checkin and checkout date. It is possible to get the website content with checkin and checkout that i've wrote in the url?
it seems more like you have to submit the form for searching checkin times and get the results from that. For that file_get_contents falls a little short (maybe not with stream context, but I haven't use those) I would recommend using curl to submit a form with the filled parameters and get the webpage result for that.