There is no iCloud app for Android, so accessing Apple's service is not straightforward. However, it's still simple, here's how
No iPhone, iPad, Mac or more generally Apple device is without iCloud. The first time you turn on the device, the configuration wizard asks you to sign in with your iCloud account - if you have one - or to create a new one. It is a requirement (however free) that brings several advantages.
iCloud in fact is the system, in fact, in the Apple cloud, that is the "cloud" where all the data associated with Apple devices go, so photos, contacts, backups and more. The point is that, consistent with the well-known "closure" of Apple to all those devices that do not have the Apple on the back, there is no iCloud app for Android devices. So if you ever find yourself in the position of having to remotely access your iCloud account and files stored on Apple's servers, you'll have to find alternative methods. It won't be as convenient as opening an app on your iPhone, iPad or Mac, but it can still be done: let's see how.
How to access iCloud on Android
First, you need to open the web browser of your choice on your Android smartphone and go to icloud.com. The page that opens contains the only effort of the entire procedure to use iCloud on Android, which is to remember your Apple ID and especially the associated password. In case you don't remember one of the two parameters, you can still retrieve it through the procedure made available by Apple, then tapping on the item Have you forgotten your Apple ID or password?
Once you've entered your Apple ID and password, it's time for two-factor authentication, for which you need an Apple device from which to approve access or alternatively you can fall back on an SMS or a call to the phone number associated with iCloud.
This is done by entering the six-number code in the page opened on the Android smartphone and, once the system determines that we really want to access and not a malicious person, it opens the "magic" doors of iCloud, but not before asking if you want to mark as trusted the Android device from which you access in order to avoid a new two-factor authentication in the future.
At this point you get to the iCloud summary screen, the one that with one tap allows you to access Mail, Photos, iCloud Drive, Notes, Reminders and Find iPhone in case you were accessing it from an Android to find your lost iPhone.
Passing Contacts from iPhone to Android
Whoever is switching from iPhone to Android may need to transfer contacts stored on the former to the latter: iCloud is a great "bridge" between the two worlds, as long as you access it from a PC or Mac.
To do this just open a browser, go to icloud.com, log in with your credentials as seen above, and once on the iCloud home screen select Contacts and then the gear in the bottom left of the screen that opens. At this point, after selecting with the mouse and the Shift or Shift key on the keyboard the contacts you want to export to Android, just click on Export vCard to start downloading them to your PC or Mac.
You then just need to transfer this file to your Android smartphone, open the Contacts app, go to Settings and look for the Import item, then point to the .vcf file exported from iCloud.