#which version
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It's between version 2.3.0 and version 3.0.5 inclusive.
If you have that version you can check the exact version number by looking in "Help menu > About Audacity".
Audacity 2.4.2 was the last version that saved projects as an "AUP file + _data folder". Audacity 3.0.0 was the first version to use the new "AUP3" project format.