We are sorry to hear about this, but please note that there are certain measures in place to ensure we avoid spam.
The moderator team has daily cases where new users join that want to spam the forum with various topics completely unrelated to 3D printing.
The requirements are explained by the Discourse bot in a message after you sign up, and following them will allow you to create new topics.
We will try to explain the process a bit better so new users can have a better experience after they login.
The current globally pinned topic explains the process to get accustomed with the trust levels, and the required steps needed to level up and be able to post.