Cross-Platform Image printing App Development

I want to create mobile app for image printing which can run on ios and android both. Only Admin user can signup a user with name, email, mobile, password, retailer name, retailer address, distance in KM and free delivery threshold in INR. Admin user should be able to upload the image with the information like size, category and price in INR. Post item sale, related stock should get adjusted. Admin user can update the stock anytime for any image. An user, post login, should be able to see different available images. On click of an image, different available size should appear along with stock availability. On selection of size, user should be able to choose work Type as 'Plain Work' or 'Jadi Work'. post selection of work Type, user can select the Quantity. On selection of Quantity, user should be presented with free delivery options based on the minimum threshold (based on delivery address) which was configured by admin during user signup process. Post this step, user should be able to place an order. Once order is placed admin should get a email and whatsapp message about the new order. The user should also have 'My Order' section to review the order.
Detailed scope and requirement can be discussed over the meeting.