how so? what error did you get? HeaderlessTSVTaxonomyFormat should be the correct format.
Again, you need to share the error to get actual support.
Though maybe you don't need to share the error hear: based on your description I am almost certain that this is a memory error — your computer does not have enough RAM to use that classifier — and so it stops running once memory capacity is reached, after one hour. This error has been discussed extensively on the forum so look through those topics to get some advice on addressing this issue. You may simply need to get access to a more powerful machine.
The trained ITS classifier that you downloaded from the forum is identical to the one that you would have produced had you trained your own classifier on the ITS sequences, and so would have the same memory requirements. So my advice is to focus on solving the memory error, rather than attempting to address the importing error.
I hope that helps!