If you created an account via Google/Email sign-in, you would have received an in-app wallet for use with the Uranium.io app.
If desired, it is possible to export your Uranium.io in-app wallet, for use in another wallet application of your choosing (e.g. MetaMask)
The steps to do this are as follows:
Sign in to Uranium.io via either the Google or Email sign-in option
Click on your wallet address in the upper right hand corner of your screen to open the account drawer
Click the wallet icon located to the right of your wallet address
Select "Manage Wallet"
Select "Export Private Key"
Copy the private key associated with your Uranium.io in-app wallet
In your wallet app of choice, import a new wallet via the import private key option, and paste your private key