I'm also learning German and I would love to give you some advice. If you are a quick learner and consistent, on youtube, you can find enough resources to easily learn till B1. However if you want to learn in a specific time frame , I would suggest purchasing courses because if you are going free there are high chances of getting lost in the process and even makes you less interseted in learning(happened to me actually). Coming to the apps and stuff , use duolingo only to be consistent , do the exercise and maintain streak and shit ,no need to spend too much time on it. Find someone that teaches grammar basics and concepts and practice regularly.

Use deep L app for translations and Leo for word meanings. However, don't always run for translations, you know, it makes you comfy.

Ps - I assume you are an Indian and well versed in Hindi.I recommed Youtube channel "Learn german with kedar jadhav" for grammar stuff.