In Salesforce Marketing Cloud most of the times you will get and below error while import/export csv,xls etc file.
Error : “Upload Error uploading, decompressing, or decrypting the file”
Resolution : Most of the time this error occurred due to there was no FTP Accounts Added. So your Administrator needs to add a new FTP account and re-attempt the import
You can refer the Knowledge Article Number 000265158 mentioned on below Salesforce help URL for detailed information and resolution steps.