Hey there PrincessChrissie,
You'll want to set up iCloud Photos on both your iPhone and Mac so that you can sync your photos across each device. Use the steps below to get iCloud Photos set up:
1. On your iPhone, iPad, or iPod touch, go to Settings > [your name] > iCloud > Photos.
2. Turn on iCloud Photos.
3. All the photos and videos in the Photos app on your device are added to iCloud. Also, any photos and videos already stored in iCloud Photos are now available on your device.
4. To view photos and videos stored in iCloud Photos, open the Photos app, then tap Library. All the photos and videos you see are stored in iCloud Photos.
1. On your Mac, choose Apple menu
> System Preferences, click Apple ID, then click iCloud.
2. Select Photos, then enter your Mac user account password if prompted.
3. Click the Options button, then select iCloud Photos.
• If you don’t see the Options button, open the Photos app to turn on iCloud Photos. Choose Photos > Preferences, then click iCloud.
• The photos and videos in the Photos app on your Mac are added to iCloud. Also, any photos and videos already stored in iCloud Photos are now visible on your Mac.
• Note: If you have multiple photo libraries on your Mac, iCloud Photos keeps only the photos and videos in the System Photo Library up to date.
4. To view photos and videos stored in iCloud Photos, open the Photos app, then click Photos in the sidebar. All the photos and videos you see are stored in iCloud Photos.
Set up iCloud Photos on all your devices - Apple Support
You can then use the guidance here to help with downloading these photos:
Download iCloud photos and videos - Apple Support
Take care!