Inquiry About billing for developer - exploring services

Hi, I am a software developer. I am following AWS machine learning learning path to explore the aws services and i want to prepare for aws machine learning speciality exam.

while exploring and creating, running some notebook instance on amazon sage maker. I got the bill of 61usd. Actually i am new to aws and i did not know the which services are free and which are not. actually sagemaker is showing in free-tier but while making some instances from following the learning path, nothing mentioned in learning video or nothing mentioned in aws console about the service which i am about to use will be chargeable. Becuase of that mis-understanding, i didn't stop some running instances and so i got the bill. Purpose was only learning. I can not pay bill. I think some testing environment should be there for developer to explore the service like google cloud provide(in google cloud i got some free credits too) So while learning we developer dont have to pay. And at the end we can prvide better service to our client - means the future clients of aws itself. As we are going to use aws for them.

can you please look into this problem and suggest some solution or assign some free credits to me.

But i strongly believe that aws has to provide prior information about charges before creating those instances for developer.

so this kind of mistakes can be avoidable in future.