Portal Knights tend to give its player a lot of different free gifts, and you can actually get these every week between Thursday and Sunday. The gifts can be received on any console, and can be obtained at any level by any character.
To get your gift, head to the first island (Squire's Knoll) and locate the mailbox on the hill. This will be glowing with an icon over it to indicate that there is a gift for you there.
If there is no gift there, the main problem tend to be that you are not offline. So make sure that your console is connected to the internet, and that you have chosen the "Online" option when opening up the game from the main menu.
There are no set rules as to what gift you get, and the developers seem to change it every once in a while. One week might be a pet, and the next week might be some building materials, and the week after you might get a piece of vanity gear. However, everyone get the same the same week, so there is no randomness to this.
So make sure to check the mailbox every weekend from now on to make sure you get all the cool stuff that the developers are giving away!