The TFT client has been axed. You can’t officially play the TFT client anymore and the only way to play is by booting up Reforged. Worst part about this is that you don’t have a choice, and that the Reforged build is a complete downgrade from the old client.
If you don’t care about not playing on BNET and want to play the old client again, check out this thread: For those who want to play Classic Warcraft 3 - #35 by Osty-1192