Mailerlite migration from Legacy to "new MailerLite" with website "booking tool"

I conduct online consultations for a fee. Marketing is currently via email, social media, and a client base we have flowing from other related offerings. I have a long-standing active MailerLite (Legacy) account. Considering migrating the account to the "new" Mailerlite in order to create a "booking website" with their tools. I have plenty of websites; don't need another one, so we'd want to integrate our current page (built on Weebly platform) with their booking tool. This current page will need some adjustments, but not a major overhaul. Here's the page with a very "clunky" registration process which I believe is inhibiting sales: https://www.wherehollywoodhides.com/live-screenwriting-consultatons.html The purpose of all this: to generate more bookings for our consulting services and to easily market and manage them via the booking tool integration, etc.