What's important to remember is that your friend MUST sign up correctly in order to receive their $10 and for you to receive credit and receive $5. Your friend must adhere to the following steps to receive the cash:
1.) Create an account using your referral link or code.
2.) Log into the Ibotta app on a mobile device that hasn't been used with the Ibotta app before. In other words, a unique mobile device.
3.) Verify a single rebate.
Once they have completed to above steps you receive immediate notification that they have been added to your account and you will receive a cash referral bonus of $5.
Some things to remember:
Just one rebate is all it takes to have $10 cash credited to your friends Ibotta account. However, the minimum payout of cash from the Ibotta account is $20 (by Paypal or Venmo transfer). So they will have to continue to use the app if cold hard cash is what they want. But there is more than one way to cash out from Ibotta. Your friends can redeem their $10 for an iTunes gift card and spend their $10 right away!* Choices are wonderful!
Clicking the referral link is the safest way to ensure that your friend receives credit for sign up. If the referral code is not added at the time of sign up then they don't receive $10 and you won't receive credit for the sign up.
*Edit: The above was true at the time of writing; however, Ibotta no longer offers $10 gift cards. They did so by raising the minimum payout applied to gift cards effectively closing this loophole.