Accounts in Quicken represent the assets and liabilities you have in the real world. You should create a separate account for each of the accounts you have in real life (like your checking account, your savings account, your credit card, your 401(k), any brokerage accounts you have, and so forth).
If you want to track the value of real-world assets, like a home or vehicle, you can create accounts for those, too. Similarly, you will probably want to create accounts for any real-world liabilities, such as a loan. Creating accounts for all your real-world assets and liabilities lets Quicken track their value and show you your total net worth.
By default, Quicken will help you set up your accounts for automatic download when available.
...