When you are playing DoubleDown Casino on your computer, you can play either through Facebook or on doubledowncasino.com. If you play through Facebook, you will only be able to use a Facebook account to play. If you play on doubledowncasino.com, you'll be able to log in using Facebook, Google, or an Email ID.
On the Android mobile app, you have the option to play logged in to Facebook, Google, an Email ID Guest account, or an unregistered Guest account. On iOS devices you have all those option as well as using your Apple ID to log in. These different account types are completely separate from each other, and there is no way to transfer or share items between them. If you selected any log in option while on your mobile device other than the one you used to play on your computer, you will be using a different account. For example, if you normally play on Facebook (using your Facebook account) but you tapped Play as Guest on your mobile device, you will be using a Guest account with a different chips balance, Diamond Club tier, and player level than your Facebook account.