I'm new to Sora 2 so forgive my question

I've been a long time Chat GPT Plus subscriber the 20 dollar plan. and I just recently got invited to use the Sora 2 platform. Explain how credits work and I noticed I have access to the old Sora model. From what I read and it's mixed but how many credits do we get for Sora 2 and how many do we get for old sora. Keep in mind I'm a paid Chat GPT member.