1) First of all, you did not connect your plugin with your MailChimp account https://kb.mc4wp.com/connecting-mailchimp-account-api-key/ Please, follow the plugin documentation step by step to launch subscription.
2) Disable plugins http://prntscr.com/pl0qg2 and contact plugin authors to solve this issue. We are not plugin developers to be in case. We are XStore theme developers and can help you only with theme options.
3) Follow the plugin documentation https://docs.woocommerce.com/document/paypal-standard/ We are XStore theme developers and can help you only with theme options.
