Each brand profile has a Media tab — a pool of videos and photos that aren't glued to any post yet. Upload in batches (drag & drop works, up to 50 MB per file), then attach items to posts from the card's From library button or by dragging in the feed planner.
Used, unused, replace
The library marks which assets are already used in posts and which are still free. Attaching moves a copy to the post; deleting a post returns library media to the pool. Replace on a post swaps its media for a new pick and releases the old one back.
You can also copy or move assets between your profiles with the transfer tool — handy when two brands share a shoot.
Storage quotas
Storage follows your plan: 0.5 GB on Free, 5 GB on Creator, 25 GB on Studio, 200 GB on Agency. The bar above the library shows where you stand; deleting posts and unused assets frees space immediately.