skate. playtest

So, I got an email inviting me to the skate playtest, I accepted it and it went on to tell me that I could invite 3 friends via their emails.

I messaged my friends but they took a bit to actually respond, and when they finally did, I entered their emails and hit the "Next" button and got a "your session has expired" text popup.

Basically I am just wondering if I can make sure the invites went through to them, as I was talking to them about getting invited to the playtest.