Hi Hassan!
This tool is still doing it’s job but there are more websites using hsts protection which is different and difficult to bypass. I would recommend to use custom kali prvided by Zaid because it has sslstrip already in it among other changes and the attack is working. In the official kali release this will not work. If you want to install it and try it anyway download it and follow the instructions from official github repository:

https://github.com/moxie0/sslstrip

Hope it helps!
Diego