You need Microsoft developer account to create WNS credentials. WNS credentials is needed to install or upgrade Windows MDM server and utilize BigFix MCM features.
To create a Microsoft developer account complete the following steps:
- Open your browser and access partner.microsoft.com
- On the following page, click Partner Center

- When you see the following screen, click Create one!

- On the following screen, click Create a new account.

- Enter your organization’s Gmail ID, email ID, or Outlook ID

- Create a password and click Next.
- Verify email: A verification code is sent to the email ID you have provided. Enter the verification code to verify email.
Once you provide the verification code, the email is verified, and the email ID you have entered becomes Microsoft account. You are automatically logged into the Partner center with your credentials.

- From the home page, click My access.
- From the Account settings page, select Programs. Under Windows, click the Get started link.

- On the next screen, click Sign up now.

- On the following page, do the following:
- Select your Account country/region
- For Account type, select the Company option.
- Fill in the contact and account verification information.

- Make the payment to purchase a developer account and proceed.
- Link partner center account with Azure AD tenant. Associate Azure Active Directory with your Partner Center account - UWP applications | Microsoft Docs




- Assign Roles if necessary. Set roles or custom permissions for account users - UWP applications | Microsoft Docs
Note: You need to register a Live or Outlook Microsoft account.
Next step: Generate WNS credetials. see https://help.hcltechsw.com/bigfix/10.0/mcm/MCM/Install/c_WNS.html