Error when accessing administration config of MailChimp module in Drupal:

Message ParseError: syntax error, unexpected 'Config' (T_STRING), expecting function (T_FUNCTION) or const (T_CONST) in Composer\Autoload\includeFile() (line 20 of /var/www/html/web/modules/contrib/mailchimp/src/ClientFactory.php)

• Downloaded latest module version
• Error when accessing the module's admin/config
• Upgraded/Switched PHP versions to 7.4, did not work
• Downgraded to previous module version, worked

• Downloaded latest module version
• Error when accessing the module's admin/config
• Upgraded/Switched PHP versions to 7.4, did not work
• Downgraded to previous module version, worked

To integrate MailChimp with Drupal 8/9:

1. Create MailChimp API Key,
2. Enter MailChimp API key in /admin/config/services/mailchimp

To create a simple MailChimp sign-up by email form in Drupal 8/9:

1. Login to MailChimp account > Go to sign-up forms
2. Embedded forms > Unstyled > (so you can custom style your own e.g. by CSS)
3. Include Form Title - Sign up to the OIC Newsletter
4. Show only required fields
5. Show format options