Whenever I try to login to iCloud it just takes me to a screen that says setup iCloud on this device.... it is already set up

The icloud website is not designed for access from a mobile device. From a mobile device you access iCloud via the apps on the device (e.g., the Files app, the Photos app for iCloud Photo Library, the Contacts app for contacts, etc).

You can force Safari on a mobile device to access iCloud.com by first attempting to go there and then touch and hold the semicircular refresh icon in the address bar until "Request Desktop Site" appears. The results won't be great as the site is not designed for mobile devices.