I am trying to connect to AWS s3 using cloudberry s3 explorer. But I don't see an option to add the AWS session token, without the session token why I try adding an account with AWS Access key and AWS Secret Key, I get below error,
But I am able to connect to AWS s3 using AWS cli. There I can specify my AWS session token in the configuration. I don't the option in cloudberry explorer

You are correct -- CloudBerry Explorer does not access temporary credentials.
It also does not recognize credentials stored in
.aws\credentials.You should either use permanent credentials (that do not include a Session Token), or contact CloudBerry Labs for assistance. Perhaps also lodge a feature request with them.