HI there @Jay Dee2610, sorry to hear about this.
When you say you can see you can install it on your s9 - are you referring to a new device or the lost one? Where do you see this exactly?
Also, when you say to access your photo gallery, had you uploaded the files to Dropbox before losing your device?
Do you see them when you log into your Dropbox account via a web browser?
Keep me posted!