Update and conclusion to my #google problem. After posting my issue to support.google.com, one person's answer led me to realize I had to use an admin@pquirk.com account, even though I had granted admin privileges to my primary email address. The other person's answer led me to a page about G suite legacy free where the button worked this time as it only works with the admin@ account. Got my emails back, will be taking them offline with Thunderbird.