dotphoto is designed to operate as a web site on iPhones. No app is necessary, and you can save dotphoto to your iPhone's home page by tapping the Save button in Safari.
Some people share photos to their friends with dotphoto, and the friends like to save a copy of the screen image to their iPhones.
Long-tapping and saving an image
The iPhone has two types of long-taps: a hard tap when you press hard on an image and a soft long-tap that provides options in the screen pictured here. Pressing too hard will NOT produce the Save Image options. Try laying your finger softly on the image for a few moments to produce this screen. Then choose Save Image to save the screen image on your iPhone.
Downloading complete albums: other FAQs
You can also sell digital downloads of the full image
iPhone's tapping system
dotphoto does not control Apple's tap interface, which Apple modifies from time to time. The IOS13 operating promises to change certain controls, so please consult Apple instructions for periodic user interface changes.