Yes, it is possible to create campaigns and ads using
web application type. Using this authentication type,
you can authenticate as any user who has been granted permission to your app and access the AdWords account data. However, it is required that you have callback URLs in order for you to use this type. Could you confirm if this is your current scenario?
If indeed this is your scenario, then you can use this authentication type, and follow this
guide on how to authenticate in the API. Let me know if this helps.