I had this issue as well. I created an account, went through the tutorial and when I was done I tried recruiting that account with my main account. It didn't work. There was no progress screen and no free pack on the new account I created. I got it work by clicking the link and then creating a new account when it asks you to create or log in to an existing account.
You (or your recruit!) has to create a new account through the recruit-a-friend link provided in-game from the button on your friends list. From there, you (or your recruit!) have to get the new account to rank 20, nothing else matters.
I recommend completing the quests and getting your free stuff. The C'Thun stuff bugged out for me, I got the quest to get the free packs, but never got them, though just from the introduction stuff I got Baron Geddon, Lord Jaraxxus, and some other cool stuff. F2P accounts are cool to play, especially when you make decks around the cool cards you have, like a aggro charge-Geddon Warrior. There's nothing better than playing a F2P deck against a long-time player only to burst them down for a bunch of damage with a charging fire elemental.
I did a new account, and IT RECEIVED the pack from being recruited (witch confirms the recruitment). But when i LVLd up to a LVL total of 20, my main account NEVER RECEIVED the friggin' skin. HELL NO im trying it all out again, fuck. MAD AF rn