If you cancelled out or for whatever reason cannot get VS Code to launch a new browser window to authenticate your org do the following from command line:
lsof -i tcp:1717
kill -9 <the process ID>
Instructions are here: https://developer.salesforce.com/docs/atlas.en-us.sfdx_dev.meta/sfdx_dev/sfdx_dev_troubleshoot_cancel_auth.htm
Sounds easy to remember…but then a couple months pass and here I sit wondering why I cannot find this page on the googles.