I have photos on Lightroom, when I want to use on in Adobe Express it says there are no photos there. What am I supposed to do? ALso no documentation anywhere on using these products together that I can find.
Lightroom's cloud storage is a different space than Creative Cloud storage that Adobe Express may use.
Or if you are talking about Adobe Photoshop Express, that is also not directly integrated with Lightroom.
Either way, you can export images or PSDs from some Adobe Apps to your camera roll or iOS Files app, and import into Lightroom from there, relying on manual export/import to pass files between Adobe's apps.
Lightroom does integration with Photoshop on iPad, but that doesn't sound like what you need.