If you want to suggest a plugin, a mod or a modpack that should be added to Aternos you can do that on our forums.
We've opened an extra section there only for resource suggestions.
Before you can create a suggestion you need an account on the forums, you can log in or register in the upper right corner. Please note that you are required to create a separate account, you are not able to login with your main Aternos credentials.
Please have a look at our guide on how to write a good suggestion. Requests not following that guide will be denied.