Without knowing what problems you're seeing, there are a few things that could be wrong.
If you're failing to even see MP3s as a thing you can import, look at the import file type, to make sure it's set to either be MP3, or to be any supported file type. If it's specifically set to say OGG (which sometimes it seems to default to), then MP3 won't be listed.
If you managed to import the MP3s, but they are silent or sound strange, try setting the MP3 to be 44.1 KHz, 16 bit, and also fix data rate not variable data rate.
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