I'm using Microsoft Graph to create a new user in my Azure AD. I'm using Graph Explorer to do so, I'm doing a POST request to https://graph.microsoft.com/v1.0/users with the following son in the body:

{
  "accountEnabled": true,
  "displayName": "displayName-value",
  "mailNickname": "mailNickname-value",
  "userPrincipalName": "upn-value@tenant-value.onmicrosoft.com",
  "passwordProfile" : {
    "forceChangePasswordNextSignIn": true,
    "password": "password-value"
  }
}

I keep getting the error: 'No HTTP resource was found that matches the request URI https://outlook.office365.com:444/profile/v1.0/users..'

I dont find anything about this error in google, why is this about? Why is the request URI 'https:/outlook.office35.com:444..' if I'm making the request to 'https://graph.microsoft.com..'?

You can't create "users" with an MSA, each account is a single user. You also cannot create a user in an AAD tenant without User.ReadWrite.All or Directory.ReadWrite.All permissions. Both of these will require consent from a tenant administrator.