How Do I COPY photos onto an external drive-- not a time machine? I want to keep the photos in the Photo App.Your support is VERY UNCLEAR

Hello,

This support article makes it more clear. The process is super easy.

Back up the library in Photos on Mac - Apple Support

"Back up the library in Photos on Mac

Even if you use iCloud Photos, it’s important that you always back up your library locally using one of the following methods:

• Use Time Machine: After you set up Time Machine, it automatically backs up the files on your Mac. If you ever lose the files in your Photos library, you can restore them from the Time Machine backup. For more information about setting up Time Machine, see Back up your files with Time Machine.

WARNING: If a Photos library is located on an external drive, don’t use Time Machine to store a backup on that external drive. The permissions for your Photos library may conflict with those for the Time Machine backup.

• Manually copy your library to an external storage device: Drag the Photos library (by default in the Pictures folder on your Mac) to your storage device to create a copy. 

If you have more than one photo library, be sure to back them all up.

Important: If any of your image files are stored outside your photo library, those files (known as referenced files) aren’t backed up when you back up your library. Be sure to back up those files separately. To make it easier to back up all your image files at once, you can consolidate referenced files into your library. See Change where Photos stores your files."

I hope this helps.

If you want to transfer the photos to another computer and continue to use the Photos.app to manage your photos, copy the Photos Library to the external volume. Only by transferring the library you will save the work you have done in Photos, all your albums, folders, adjustments, metadata. the external volume has to be compatible with Photos. How to prepare the external volume is described here: Move your Photos library to save space on your Mac - Apple Support

The external volume must have the file system format APFS or MacOS Extended, the volume must not have been used for Time Machine backups and should have a wired connection, not a network access. make sure, the flag "Ignore ownership on this volume" is enabled in the Info for the volume.

• Quit Photos, if it is running. Then drag the Photos library from the Pictures folder, or wherever you are storing it, to the external volume. test it thoroughly if it is working properly by double clicking it to open it in Photos. Check, if you can open individual images and view them enlarged and add adjustments.
• Quit Photos again, then eject the external volume and connect it to your new Mac. Now drag the saved Photos Library to the Pictures folder on your new Mac and test it in Photos.

I'm wondering what if I delete photos on my phone after I sync to my Photos app on Mac, then I sync it again.

Does the photos on my Photos app on Mac will be delete too or remain?

Are you syncing via iCloud?

No, I'm syncing via cable.

I just took some photos of my pay slip, and want to put them in a folder.

I just took some photos, I want to put them in a folder?