The only quicktags module I found doesn't have a version for Drupal 6 and Drupal 7; the module is for Drupal 4.7 (the development snapshot 4.7.x-1.x-dev) and for Drupal 5 (the development snapshot 5.x-3.x-dev, and the official release 5.x-3.1-dev).
If you copied one of those versions, the module is rightly reported not to be compatible with Drupal 6.
If you installed Quick Tabs, which effectively has a 7.x-3-0 version, then it is probable that you have two copies of the files of that version in two different directories, one of which is the directory of another module. Suppose that you copy the files of the Quick Tabs module in the directory "cck," those files will be found first the files contained in the directory "quicktabs"; if the files copied in "cck" are for Drupal 7, then you see the error you are seeing because those files are the first ones that are retrieved.