Some hosts have security options in place to stop uploads of files. With my host, I just opened a support ticket and it was solved.
I just tested out TBS there now and successfully published a post on my blog. However, this only uploads one file each time. It posted a correct title, spun from the titles in TBS and then posted the text in the correct place in the blog. In order to publish another article, you would need to operate the "post to blog" again. You do not need to generate the articles into a file, the post to blog chooses one article and posts it for you. I saved the spintext on my computer, posted an article, closed down then tried again a few hours later from a different computer, with the same saved spintext. It posted a different article. I posted 4 articles on my blog (and then deleted them) and they were all different, however, if you close and open TBS at another time, I assume it is possible that you could get 2 articles the same because I don't think it remembers what it posted after it is closed. This should be a very low risk with a large spintext file.
Hope this helps.
In the past, I used a paid-for WP plugin from Amin Motin called Feed me. It allows you to upload a zip file of articles and publish them at a schedule of your choice (hours or days or weeks). I have had a look on Word press at the available plugin options and don't see one exactly like this. I created a zip file containing various articles, like those from TBS and published them on my blog automatically over a few days. The files MUST be plain text, no images.