how to convert xlsx or csv to qfx for importing

Quicken doesn't support importing Excel or CSV files they have to be converted to QFX or QIF format.  You need to find a program to convert them. Here is one such program:
FAQ: A program to add the account name and type to QIF files so that Quicken will import them. — Quicken

rdschmid said:

Chris_QPW is there a reason your website is insecure? i.e., not HTTPS?

Yes,. It costs extra money to have a certificate and pay for a secure website, and there is nothing on that site that requires a secure connection.

EDIT, NOTE the actual program download of importQIF comes from a secure connection to Amazon web services.  For the Quicken patches that are also on that site they come from a OneDrive share that is also a secure connection.