When you create a mapping that runs on an advanced cluster and contains a complex file target, the Target transformation creates a folder with the file name you enter in the File Name property in the Advanced area. It does not create a single file. This is necessary because the output may be divided into a series of files.
The folder name might also be appended with a unique identifier. You do not need to know the identifier, because the mapping recognizes the file name and all the contents within the folder.
The part files within the folder are named:
part-<unique identifier>.<format>
, where the suffix can be csv, txt, avro, parquet, json, orc.