Overview
Mass posting is built for situations where you already have a large batch of photos, videos, or files and need to place them into the schedule quickly. Each uploaded file becomes a separate post.
Telegram bot
The usual flow is to choose a stream, upload a batch of media, let each file turn into its own post, and then let Posterium distribute the posts into schedule slots.
Mini App
In the Mini App, this scenario is secondary: it is more useful for checking the result than for launching the bulk upload itself. The main workflow still belongs to the bot.