Have followed instruction, grab auth key from shipstation in woocommerce, paste in shipstation add new store dialog, input url of store (tried tld first, then direct to /shop/ url) submit and error, no details on error. Host search error logs on host and found issue is 400 error, and found authentication key at issue. Any help please. I even redownload plugin in WooCommerce.com and reinstalled over first plugin and still error. Disable security on site as well, same issue.
I am glad to see that you've reached out to our support team already! This is absolutely the right call when an authentication fails.
Additionally, if any of our other wonderful community members have gotten through this on their end, please let @TierOne and the rest of us know how you did so 🙂