If you are not familiar with how to download an (S)FTP client, please follow these instructions:

Go to https://filezilla-project.org/ and download either the mac or windows version.

After installation, please write the FTP account details (Host, User and Password) previously provided to you, in the blank spaces at the top of the software’s page as shown in the image below:

When the FTP account has loaded (see image below),

you can just drag and drop your files on the right column shown here: