Thank you to @Anibru as his/her solution appears to have worked for me.
I have MacOS Monterrey 12.21. On the Schwab login screen that is within TT, there's a tiny message at the lower left that it only supports Microsoft Edge, Google Chrome, and Firefox browsers. Since my default browser was Safari, here's what I did:
1. Download Microsoft Edge and set it as the default browser
2. Close Safari, Edge, and TT Deluxe applications
3. Relaunch TT
4. Establish connection to Schwab. You may still get an error, but after a few times, it should connect (it may be a bandwidth issue as the Schwab Tax Forms were just made available as of 2/18/22 and likely there are a lot of users trying to access.)
5. If error persists and you have Two-Factor Authentication (TFA) activated on Schwab, try deactivating this first before connecting via TT (even though Schwab site states that you don't have de-activate TFA). After successful download to TT, re-activate TFA.
Hope this works for you. Good luck.
