Is there a way to Collect the emails from Forum Sign Ups and ideally have them automatically import into my MailChimp or MailerLite accounts?
If not, is there a Excel File for easy download and upload?
wpForo users are the same WordPress users. So the emails are located in WordPress users system and users tables. So you should search solution in WordPress plugins. The MailChimp or MailerLite WordPress plugins should have an option to get WordPress users emails too.