created new account but free tier credits are not available

Hello.

AWS free tiers are not given on credit.
The one-year free usage quota is given based on time units, size of storage used, number of API requests, etc. when using the AWS services listed in the following documents.
For example, if you are using EC2, you are given a free tier of 750 hours per month when using the t2.micro instance type.
https://aws.amazon.com/free/?nc1=h_ls&all-free-tier.sort-by=item.additionalFields.SortRank&all-free-tier.sort-order=asc&awsf.Free%20Tier%20Types=*all&awsf.Free%20Tier%20Categories=*all

Usage alerts for the free usage tier can also be set up, so there is a mechanism to use this to notice charges before they occur.
https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/tracking-free-tier-usage.html