No, it is not necessary to get user opt-in via the ATT policy in order to use Branch or load the Branch SDK.
There are numerous uses for UX and analytics tools (such as Branch) that do not fall within the scope of Apple's policies against tracking. Until/unless you receive ATT opt-in from a user, Branch helps you stay in compliance with the policy by not activating the functionality in our platform that provides device-level ad measurement.
For more details, please see:
Updated almost 2 years ago