You write that it works with scan_csv. Looking at the documentation scan_csv seems to be the only option to support reading multiple files (with glob pattern).

read_csv: Read a CSV file into a DataFrame. (also accepts glob pattern via glob=True).

scan_csv: Lazily read from a CSV file or multiple files via glob patterns.

You might also need to pass the corresponding session token as follows.

import polars as pl
import boto3

profile_name = "your-profile"
s3_path = "s3://my-s3-bucket/my_file.parquet"

session = boto3.session.Session(profile_name=profile_name)
credentials = session.get_credentials().get_frozen_credentials()

df = pl.read_parquet(
    s3_path,
    storage_options={
        "aws_access_key_id": credentials.access_key,
        "aws_secret_access_key": credentials.secret_key,
        "aws_session_token": credentials.token,
        "aws_region": session.region_name,
    },
)

From the AWS access keys documentation:

Specifies an AWS session token used as part of the credentials to authenticate the user. You receive this value as part of the temporary credentials returned by successful requests to assume a role. A session token is required only if you manually specify temporary security credentials. However, we recommend you always use temporary security credentials instead of long-term credentials. For security recommendations, see Security best practices in IAM.