In simple terms:
Each 3 months (Quarterly means 1/4 of a year), the systems looks up if your account balance (the money you earned on Upwork) reached $1,000 or not.
If you earned $1,000 or more, it will automatically withdraw the funds to your bank account.
The next lookup will be the 28th december for you.
You can also change that schedule and you can withdraw your balance at any time with the "Get Paid Now" button.
Not sure if you can add another bank account. You can try it by clicking the "+ Add a Payment method" button.