Web sites usually ban a user's Internet Provide (IP) address. TOR changes your routing path every 15 minutes, meaning that your apparent IP address changes every 15 minutes, too. If one of those addresses was used previouusly by someone who was banned from the same site that you want to use, the site computer will think that you are the same "person" whose IP address was banned. So, to fix this, you can click on the green onion icon in the upper left corner of your TOR browser and select "new identity." This will force the browser window to close and reopen with a new IP address in a couple of seconds. Voila! You are now using a new IP that will probably work at the site (unless it has been banned, too). Also, some web sites permanently ban IP addresses that are know to be used by TOR. In that case, you can set up an account with an IP proxy service other than TOR, but that is more complicated.
By the way, congratulations on your determination to avoid getting tracked, traced and database!