This is the bit most people miss. Download
Edits:
iPhone —
App Store
Android —
Google Play
In the
top-right menu, enable
4K and set it to
HDR. Then tap the
Instagram icon (bottom left) to upload straight out, and add your caption and tags there.
Apple devices are generally better optimised for this, so use one if you can — iPads and other Apple devices will most often work the same as an iPhone. If you’re on Android, just use the Edits app there instead.