Raspberry Pi web server Hostname

Ok, so i am a noob at this wordpress stuff. But I do have a local wordpress server up and running on a Raspberry Pi 2. It looks like it’s working properly because I can access the WordPress Admin Dashboard from the raspberry pi’s ip address over my local network just fine. However, when I try to add a new theme or update the plugins I’m asked to put in the “Hostname” “FTP Username” and “FTP” Password”

Now, I thought that either the Raspberry Pi’s local ip address or “localhost” would be the correct hostname but neither of them seem to work. I do know my FTP username and password are correct because I can connect just fine using them with filezilla.

Am I missing something obvious here?

Thanks!