Invite codes are typically used for referrals and promotional access. Placement can vary by app version.
Common reasons include expired campaigns, region restrictions, entering the code in the wrong field, or the account already being registered without a referral.
Some platforms allow it for a limited time, others only during sign-up. Check the app referral rules for your version.
Not always. Bonuses depend on the current promotion, your region, and eligibility rules.