Export contacts from Ninox to MailChimp

Set a table view to include the fields you want to export.  ie name/ address , emails etc

filter the table to show what records you want to export.

Then use the Gear wheel option and select export data to csv files

Mail chimp will read it no problem ( I do it every week) as you can see i have a view dedicated for mailchimp . in my form I have a couple of files GDPR opted in and a field yes/no to say include in mailchimp

Both must be true to show on the table view and thus for export