We used Box Sign Ready Sign link to confirm completion of an HR course. The link triggered the signer to authorize through their SSO (Okta) and create a Box account because they have auto roll-in enabled. We only noticed this because of a huge spike in overages one week. The immediate fix is turning off auto roll-in but that's not good for obvious reasons. TL/DR: Using Ready Sign Links, with an SSO, with Auto Roll-In enabled, will cause cause a spike in overage.