Broadcastify’s mobile ecosystem is split. The (iOS/Android) requires a separate purchase to remove ads, but it does not grant you Premium server access.
If you're looking for a way to test Premium features before committing, you might contact Broadcastify support directly to ask about any unpublished trial options, but don't expect one. broadcastify premium free trial
Upgrading (or earning) a Premium account removes ads and unlocks several features: Feed Archives Broadcastify’s mobile ecosystem is split
Signing up for the Broadcastify Premium Free Trial is easy: broadcastify premium free trial