Upload Customers from Spreadsheet - error

Hello,

Facing a couple of issues while trying various options. Requesting your assistance.

First Issue:

If I download the template, fill up the data, generate zipped and csv files, upload the zipped file, I am able to get past the error.

However, if I directly prepare the csv files (instead of starting from template), zip it, upload it, am getting the below error.

Second issue:

If I upload customers by using erpintegrations REST API option (importBulkData), seeing either one of the below two error messages from Tools > File Import and Export.

• The zip file contains data file with invalid extension:aruploadcustomers There were no valid data files found in the zip file . Only .dat , .csv , .xml