Apple wants you to use its photo storage service – and its music service, mapping service, and messaging service – rather than anyone else’s, and there isn’t really any options to output your files from Apple Photos to iCloud as there are in Google Photos. You can download individual photos and videos from iCloud on the web, but it will probably take you a long, long time.
Your best approach here is to install the app you want to transfer your photos and videos to on your iPhone, iPad or Mac, and forget about the middle step of downloading all your files to computer. You need to make sure that all of your photos and videos are stored on the device of your choice, and not in the cloud. To do this, go to the iOS settings and choose Pictures then Download and keep originals, or open Photos on macOS and choose Pictures, Preferences, iCloud, and Download the originals to this Mac.
If you know that all of your photos and videos are on your computer or mobile device, you can move them elsewhere by installing the appropriate app: Dropbox for ios or macOS, for example, or OneDrive for ios or macOS. If you have access to a Windows computer, you can use iCloud for Windows to sync all your files to the local hard drive before uploading them elsewhere.
Like Apple Photos and unlike Google Photos, OneDrive doesn’t have a mass export tool to download all of your photos and videos at once. You can select and download bundles of files via web interface or the mobile app, but if you have thousands of images and video clips to transfer, it’s not really convenient to transfer them all like this.
If you’re using OneDrive for your files, we’ll assume you have access to a Windows laptop or desktop. You can make sure that all of your photos and videos are synced locally on this computer by opening OneDrive in File Explorer, then right-clicking the folders containing your images and videos and choosing Always stay on this device. You can then install another app –Dropbox, Google backup and sync, iCloud for Windows– and point it to those OneDrive folders.