If you are trying to upload a .wav file and you receive an error related to a mismatched RIFF Chunk Size then this means that your audio file is corrupted and cannot be used for processing.
Specifically, the audio file's metadata itself is declaring that the file size should be a certain size whereas the actual file's size is different than that size (Meaning there is most likely missing data, and thus, a corrupted audio file).
In order to fix this issue, you will need to re-encode your audio file from the source masters or have your sound engineer export new files for you and try uploading again.