In the Contacts tab, go to the group you'd like to export. Once in the group page, click on Export Contacts.
When the modal pops, confirm the export. You'll receive an email with a link to download the CSV file with your contacts.
Note: The CSV file will have the same format as the upload file template (in case you want to re-upload the file later to another group).
If, when opening the CSV file, the numbers of the mobile contacts appear in a format similar to 6.14E+10, simply just expand that column and you'll see the number appearing correctly.
Downloading All Contacts (active + unsubscribed)
If you download from the All Contacts group, the CSV will contain only your active contacts.
If you want to download your complete database (both active and inactive), you'll need to export your All Contacts group and your Unsubscribed group separately.