I opened a new Chase Bank account last spring, but did not set it up in Quicken until today.

Your FI or bank controls how far back you can download. Most only go back 90 days. The rest you will have to enter manually. You might get a greater range of transactions if you go to your financial institution's website and download a different range of dates in a Web Connect .QFX file. If you manually enter older transactions, be sure to adjust the opening balance to account for them as you enter them.

See this FAQ on downloading older transactions,

https://community.quicken.com/discussion/7160091/faq-download-old-transactions