A scammer will ask to chat with you on another media platform (ex. Discord), saying that they know how to generate free items for you. At some point, they'll ask you to download an extension (cookie manager). One said extension is called EditThisCookie.
Once you download it thinking that it's harmless and helpful, the scammer will ask you to give them your Session ID. Once you give them your Session ID, they have all the information they need to access your Animal Jam account.
A scammer may send you a suspicious link to an unknown website on another media platform. Once you click on the link, the person who sent you the link will get your Session ID and will be able to see some of your personal/private info, this include passwords and other stuff.
How to avoid this hack
Do not download anything that anyone tells you to, and do not give anyone technical information. If someone asks you to download something or give information, they are trying to hack into your account. If you suspect that a link someone sent you is suspicious, do not click on it! Even if you are curious to see what the link leads to.