Can’t access Adobe Commerce on cloud repo: 403 Forbidden or 404 Not Found error when deploying

To obtain valid authorization keys (skip this if you are sure your key is valid):

1. Contact the Adobe Commerce license owner to generate the keys if you were using those created under a shared account. If your license was previously revoked due to payment issues but has since been renewed, you will need to generate new authentication keys.
2. If the account owner is unable to log in to the Commerce Marketplace, submit a support request at Adobe Experience League for further assistance.
3. If the login is successful, check the MAGE ID at your Commerce Marketplace to ensure it is associated with the current account owner’s email address. If the Mage ID is associated correctly, submit a support request at Adobe Experience League for further assistance. If not, submit a support case directly to the Marketplace team by visiting the Adobe Commerce Marketplace site, navigating to the bottom of the page, and clicking Contact Us  to open a form for submitting a Marketplace support ticket.
4. If that doesn’t work, send an email directly to Commerce Marketplace Support to request an update to the email address associated with the MAGE ID.

Add the keys value in the env:COMPOSER_AUTH variable (or make sure that the correct value is there) and check if the keys are specified consistently in the variable on the project level and environment level as well as the auth.json file (if it exists) in the project root. See the instructions and related information in Prepare your existing system and Add authentication keys in the Commerce on Cloud Guide.

Update or deleteauth.json, to have a single place where the key is configured, if the authorization keys values are not specified or have another value. Log in to the machine that has your Adobe Commerce on cloud infrastructure SSH keys and then log in to your project: magento-cloud login

Create a branch to update the code (in the following example the branch name is auth is created from the primary branch): magento-cloud environment:branch auth master

Change to the project root directory.

Optional: Delete the auth.json if you prefer and continue to step 10.

Open auth.json in a text editor.

{
             "http-basic":  {
                 "repo.magento.com": {
                     "username": "<public_key>",
                     "password": "<private_key>"
                     }
                   }
                 }

Add the correct authentication keys.

Save your changes and exit the text editor.

Commit and merge your changes:

git add -A
        git commit -m "<message>"
        git push origin master

Wait for the project to deploy.