How do my edited photos reach my iPhone?
Start with the photos you have finished in Lightroom Classic. With LR to Photos, add them to a published collection and click Publish. The plugin exports the finished versions and imports them into a matching album in Photos on your Mac.
With iCloud Photos enabled for that library and on your iPhone, using the same Apple Account, your photos and album are available in the iPhone Photos app too. You do not need Lightroom installed on the phone for this route.
Does Sync with Lightroom do the same thing?
No. Sync with Lightroom sends selected Classic collections through Adobe’s cloud to Lightroom on your other devices. Classic uploads Smart Previews for this workflow.
That can be useful if you want to browse in the Lightroom mobile app. It does not automatically create albums in Apple Photos. To put an image there from Lightroom on iPhone, you make a separate export using Save copy to device.
Can I do this without a plugin?
Yes. Export your selected finished photos as JPEGs from Classic, then import those JPEGs into Photos on your Mac. Choose or create the destination album during import. With iCloud Photos set up, they can then appear on your iPhone.
That is a sensible option for occasional batches. LR to Photos brings the export, import and album destination into Classic’s Publish workflow when you do this regularly. Follow the manual export and import steps.
Which Photos library should I use?
Use the Photos library you normally sync with your iPhone. On Mac, iCloud Photos works with the System Photo Library. Keep the same Apple Account on both devices and make sure iCloud Photos is enabled.
If you already see your iPhone photos on your Mac, you may already have the connection you need. Start by publishing a small selection to that intended library. You do not need to create another Apple Account.
Enabling iCloud Photos applies to the library as a whole. If you use several Mac libraries, read Apple’s System Photo Library explanation before changing which one is connected.
What about iCloud Drive?
Putting JPEGs in an iCloud Drive folder makes them available as files. It does not by itself add them to your Apple Photos library or create a Photos album.
For photos you want to browse and share from the normal iPhone Photos app, use the Photos workflow above.
A photo is missing from my phone. What should I check?
Check whether the finished image is in the intended album in Photos on your Mac. If it is, read the Photos library’s sync status and check that both devices use the same Apple Account. Apple’s status guide explains the message you see.
If it is missing on the Mac too, check the publish result in Classic and follow the connection and setup steps.