I'm afraid you can't. Even if you buy PictureNFTizer Agency without the Standard Version, you will not be able to login.
Here is why:
1. PictureNFTizer Standard is the main product which is either a Monthly, Yearly or One Time Subscription.
2. PictureNFTizer Agency is an Upgrade or Up-sell which adds the Agency features in your PictureNFTizer account.
3. Since PictureNFTizer Agency is not independent, you will need to subscribe for the main product PictureNFTizer Monthly, Yearly or One Time subscription first. Else you can't login with only PictureNFTizer Agency in your account.