How do I improve myself at work?

I am a fresher and it has been 3 months I have joined a renowned software company here. Now 3 months later, the HR is telling me I am underperforming very much and might get kicked out soon if I don't improve myself. I have been learning and trying to apply my knowledge on my project as much as I can. I have identified my problem which is :

I have to work in an existing project where I have to work in Django and Django REST Framework. I have no prior knowledge of web development and I have never worked with API's. I have watched my tutorials, know the basics. But the project seems completely different and I often lose clue how to proceed. I have to ask for help every now and then as I don't know how to think, as I have no prior experience with API or web development. Even the juniors joining my team are performing very well as they have freelancing experience, but all I have is problem solving experience.. which is making me frustrated. How to improve this situation ?
n.b. I am very frustrated so please answer and don't mock, thanks 🙂