Help with Icloud

So this is not such a tedious process but my assistance would be to grab your Mac or PC first and then follow these steps:-

Step 1. Using your Mac or PC, go to icloud.com.

Step 2. Enter your Apple ID and password to log into your iCloud account.

Step 3. After logging in, click on the "Photos" icon.

Step 4. In iCloud Photos, switch to the Photos tab > select the photos you want to transfer and click the download icon.

Step 5. In the next window, select the USB drive or external hard drive in the left pane and click the "Save" button on the bottom right.

If these steps are properly followed then it should work, if there are any more discrepancies don’t hesitate to ask again!

Make sure they are synced with a computer then back up the computer as in How to back up your Mac - Official Apple Support.

Either that or log into iCloud, open the Photos app, select all the photos, then click the download icon and select the external drive as the destination for the zip file that will contain all the photos.