Along with configuring the file manager app on your mobile device, you do need to confirm that file sharing is enabled on your laptop. Which operating system is it running? Linux, Mac, or Windows?
Also, if you have a third-party firewall running on your laptop you might also need to open a specific port that corresponds to its file sharing (often specified as to which during the set up process you need to do).
And of course, both your laptop and mobile device need to be connected to the same local network for any kind of local file sharing.