Before you deploy to production, it’s required to make a merchant agreement. You can submit the form via. https://merchant.monpay.mn/mn/online-register
If you need support during your development, contact us by sending an email to firstname.lastname@example.org , "Developer support in the subject line. Please make your inquiries as clear as possible, attach screenshots if necessary and don’t forget to include your phone number, so that we can give you a support quickly.
If you’d like to discuss about business opportunities such as marketing, collaborative promotion, contact us by sending an email to email@example.com , "Marketing support" in the subject line.