After updating to Mac OS 10.15.6 I am unable to download files from the internet using either safari or chrome

How much free space on your drive?

Does the same problem happen if you boot in Safe Mode? (Note: Safe Mode is sloowww, and not to be used permanently; but by testing in Safe Mode we can determine if the problem is caused by some third party software).

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

More than one antivirus app - This machine has multiple antivirus apps installed.

 Antivirus software: Apple, Avast, and Malwarebytes

Your mac does not need a third party antivirus, let alone more than one.

Avast is terrible. Uninstall it.

MalwareBytes is a decent program, but should only be run manually in case there is some suspicion of adware. There is no reason to have it running permanently.

To make matters worse, you also have remnants of symantec still there.

Plus several old stuff.

You also have Monolingual - this is used to "delete unused languages" but you should NOT do that.

I am sorry to say this mac installation is a mess.

You should really do a full backup or preferably two, then erase and install.

After that, you can migrate back the user accounts ONLY - otherwise you'd be bringing all the problems.

I'm having similar trouble. Here is my Etrecheck report