Small Flutter IPhone App with Back End

I need someone with experience to create an Audio flutter app for iphone with a backend to manage the content. The budget is $500 (I can not give more but i will need a website and a android version after so you can consider this on the long term.) There is 4 pages (Story Audio page, Ambiance Audio page, Audio Player page, Account Page. I don't need a login. Front End Features: 1. Push notification for new added audio 2. Slider to browse the audio thumbnail (left/right) 3. Navigation menu (i created 3 json files to animate the page transition on clicked button) 4. Allow the user to pay to unlock all the audio (yearly payment / Only One Price) I need the slider to animate similar as the video in attachment in this job post (Something cool) Back End features: 1. Allow me to add/remove Audio with Thumbnail in the slider 2. Allow me to add/remove Audio with the thumbnail at top page where you see the "New" thumbnail. 3. Allow me to select which audio must be locked/Unlocked (When locked, the apple payment must open) 4. (If possible, Add a section to show who upgraded but i am not sure if it is possible because i don't want to offer a registration page) For the animation, if you can not animate something with flutter, tell me and i will provide you json files (I will work with you during the process for the design part). Code: Dart / Flutter Back-end: Firebase I include in this job post: video of a animated slider i like (I saw some similar in the flutter libraries so i think it can be tweaked to look like that one) + a dummy to see the structure. Thank you