It's probably because you signed up with an existing google acc or other accs and didn't really register with an account from scratch. When you register from scratch, the part where you put the code should show up before you finish registering.
did you sign up using your phone?
make sure that you're signing up in the app (not in the website) ...before the app proceeds you to the main platform, something will pop up where it will ask you to type your Display name and below it was where you can type the invitation code so you'll receive a free inks.
if it does not work, maybe you try again using another new acc? You can use my invitation code ZESC635P
You can check this tutorial
https://m.imgur.com/a/luPIE3s
No I don't use any existing account like g..le or fa**ok, i made a new account with my email.. i looked everywhere but it doesn't show an option to enter a code :(
Thank you, I already look the tutorial.. I signed up on the web and later I downloaded the app and sing in on it, but I never got the option to enter the code.. maybe later I will made a new account jajaja ╥﹏╥
Somebody else can't find where to put the code for free ink?? I already downloaded the app but I can't find where to put the code, I already completed my profile but it doesn't appear any option to put a code jajaja :(