How do I access Find My Friends from iCloud.com?

I have been reading that it is now possible to access Find My Friends from iCloud.com, and I have a friend who is able to do so from their iCloud.com account: It shows up in the iCloud menu under the URL "icloud.com/#fmf". But when I log in this URL silently chops off the "fmf" part, the "Find My Friends" app doesn't show up from the menu, and when I try to use an invite from my friend, it tells me to install the app on my iPad.

I don't have an iPad. In fact I don't have any mobile devices which are made by Apple, which is the whole point of wanting to use iCloud.com.

How do I get Find My Friends to show up on my iCloud.com account?

Update: I found that I can enable iCloud on my Mac by going to System Preferences -> iCloud and signing into with Apple Id. After I do this, icloud.com/#fmf works to the extent that it brings up a map, but I still can't see any friends. Then, when I try to click on the link in the invitation from my friend, I get the following message:

Find my Friends

To view <friend's name> (<friend's e-mail>) location, open your
invitation in the Mail app on your iOS device and tap View Request. If the 
Find My Friends app is not installed on your device you can download it
free from the App Store.

Well.... once again I don't have an iOS device, and if I did I don't know how I would open the invitation in the Mail app, because my Apple Id is linked to a GMail account, not an iCloud account!

You can't to my knowledge. Find My Friends (sadly) requires an iOS or OS X device be configured for use with Find My Friends at least once. If you have no Mac or iOS device, you can't. If that article wasn't clear enough (it's rather vague) here's a more explicit one.

Note: If you don’t see Find My Friends on iCloud.com, your account just has access to iCloud web-only features. To gain access to other iCloud features, set up iCloud on your iOS device or Mac.

After you do that, then you can access it from the web.