Pre-authenticated requests provide a way to let you access a bucket or an object without having your own credentials. For example, you can create a request that lets you upload backups to a bucket without owning API keys.
When you create a bucket, the bucket is considered a private bucket and the access to the bucket and bucket contents requires authentication and authorization. However, Object Storage supports anonymous, unauthenticated access to a bucket. You make a bucket public by enabling read access to the bucket.
pre-authenticated requests have to select expiration date

https://docs.oracle.com/en/cloud/paas/autonomous-data-warehouse-cloud/user/connect-intorduction.html#GUID-CD4C10A6-1C1E-4969-8F67-1433B6CE626A To download client credentials from the Autonomous Transaction Processing Service Console:
- From the Service Console click the Administration link.
- Click Download Client Credentials (Wallet).
- On the Download Client Credentials (Wallet) page, enter a wallet password in the Password field and confirm the password in the Confirm Password field. The password must be at least 8 characters long and must include at least 1 letter and either 1 numeric character or 1 special character. This password protects the downloaded Client Credentials wallet.
- Click Download to save the client security credentials zip file. By default the filename is: Wallet_databasename.zip. You can save this file as any filename you want. You must protect this file to prevent unauthorized database access.
The zip file includes the following:
tnsnames.ora and sqlnet.ora: Network configuration files storing connect descriptors and SQL*Net client side configuration.
cwallet.sso and ewallet.p12: Auto-open SSO wallet and PKCS12 file. PKCS12 file is protected by the wallet password provided in the UI.
keystore.jks and truststore.jks: Java keystore and truststore files. They are protected by the wallet password provided while downloading the wallet.
ojdbc.properties: Contains the wallet related connection property required for JDBC connection. This should be in the same path as tnsnames.ora.

Explanation
You can use the Console or API to export images, and the exported images are stored in the Oracle Cloud Infrastructure Object Storage service. To perform an image export, you need write access to the Object Storage bucket for the image.