If you have already authenticated with Google but want to download a google spreadsheet from a different Google Account, follow these steps:
Choose “Reauthenticate With Google” in the Window→Localization Editor→Import Spreadsheet Menu.
Choose “Go to Google Authenticate URL.” The google authenticate prompt should open in your browser.
Grant Access to Localization Editor. The google authenticate will ask you to grant access to your files. Click Accept to continue the authentication process.
Copy the access code from your browser and paste it into Set LE Access Code window.
Select the Spreadsheet to Import and click “Download”