Why is my MacBook Pro not connecting to the internet?

<< The apple store told me to get a wifi dongle, which I did, >>

That sounds like a great idea, but there aren't ANY simple Wi-Fi dongles that survived the jump to only 64-bit software after Catalina. We did a wide search on behalf of several Readers who needed one. Came up empty.

Real work-arounds entail creating an Ethernet interface, and then if you MUST have Wi-Fi, connecting a simple Wi-Fi device to that Ethernet.

<< When I open network preferences I get an error message. >>

This typically happens when your Wi-Fi hardware did not respond.

Sometimes a full Shutdown and Restart of your Mac brings it back.

<< I need wifi on my mac to download my information to a USB drive. >>

I don't understand that.

Where is the information coming from?

You create an ethernet by plugging an Ethernet cable into your existing ethernet jack, or by buying a USB or ThunderBolt adapter to Ethernet, which provides the Ethernet interface.

I would try resetting the router if you can. I don't know if that would help though, I haven't had a problem like this.