When setting up your eDocBuilder account to access your Pressero account and make your custom profile fields available to the Data Capture tab of your eDocBuilder templates, the custom profile files should be shown if you have entered your Pressero credentials correctly on the tab Admin > Pressero Credentials.
If your credentials are correct, and you think this should be working, it is possible that the Pressero admin user login that you have entered does not have the correct permissions enabled to see your custom profile fields.
Login to your Pressero account, go to Preferences > Admin Users and check what Admin Groups that user belongs to by editing the user and going to the Admin Group Memberships tab. Note the name of the admin groups shown there.
Then go to Preferences > Admin Groups, edit one of the admin groups for that user and check the status of the permissions Can manage reports and Can view reports.
The permissions for Can manage reports and Can view reports need to be set to be Allowed. Save that change and then go back to the Admin > Pressero Credentials tab in your eDocBuilder account and click the Reload button on the right. The custom profile fields should be showing on the listing on the right of this tab if done correctly.