Not a publishing platform. Your own reach, on your own terms.
An "author platform" is the audience and reach you have direct access to — your website, your email list, your social following — as opposed to a publishing platform like KDP, which is where your book is sold but which you don't own or control. Confusing the two is common: a book selling on Amazon isn't the same thing as having a platform, because Amazon's audience isn't yours to reach directly.
At its simplest, it's a website you control and a way to capture reader contact information directly — the two things CDMworld's Author Launch Package is built around. Social media can be part of a platform too, but it's rented space: the algorithm, not you, decides who sees your posts, which is exactly why owned channels like a website and an email list matter more over time.
A platform builds gradually, book by book and email by email. The realistic goal for a first launch isn't a large existing audience — it's putting the infrastructure in place (a real website, a working way to capture emails) so that whatever audience does show up has somewhere real to land, and so the next book isn't starting from zero.