Although you do not possess authority over resources, you are given time and budget. And with it, you must be able to deliver a product that benefits the company.
That is what is expected of you as a Product Manager.
The main activities of this role are mainly coordinating and consolidating to the many sides and personnel you have to be familiar with around the company. You have to be able to think fast enough to strategize so that the product in your mind comes to fruition after establishing a set of goals.
The one thing you must never forget is that being a Product Manager would help you develop but also requires you to have an open yet growth-oriented mindset.