I can get ahold of the person that sold me the phone and it is iCloud locked it is on the Activation Lock Screen and I can’t use my iCloud. And I don’t know there iCloud. Is there anything I can do

Unfortunately, there i nothing that you can do except enter the requested credentials to remove the Activation Lock. If you cannot get a hold of the seller to get the information then that iPhone is of no use to you.

Axel F.

Without the Apple ID and Password of the original owner, you will never be able to bypass Activation Lock a theft prevention feature. Read this link...

The All Too Common SAD Reality of Buying … - Apple Community

Return for your money back. If not possible, you can recycle it at any Apple Store.

"My iPhone 11 that I bought off of Facebook is iCloud locked I guess. Right now it is on the activation Lock Screen, I need help to try to use my iCloud. I can’t get ahold of the person I bought it off of so I don’t know there iCloud account or anything like that."

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Getting your Money Back:

Seems you have been scammed. Contact Facebook, and see if the seller can be held accountable, and if you can get your money back.

Set Rules for the Transaction:

If you cannot get your money back, then take this as a learning experience, knowing to always have the seller log themselves out of iCloud, prior to selling it to you. Once meeting them in-person, request that they let you log in to it, and associate it to your own account. If they decide to disabide by those rules you've set forth, then do not proceed with the transaction.