Matheus

I think one of the following plugins will help you:

1. https://ww.wp.xz.cn/plugins/wp-user-frontend/

2. https://ww.wp.xz.cn/plugins/user-submitted-posts/

3. https://ww.wp.xz.cn/plugins/accesspress-anonymous-post/

4. https://ww.wp.xz.cn/plugins/ppress/

Good luck!