The documentation portal is undergoing maintenance. During this period, you can't create any new user credentials. If you do, you'll need to recreate the user credential after the maintenance period ends.
When you work with versioned objects, you must check out an object if you want to change it, and save it when you want to commit the changes to the repository. You must check in the object to allow other users to make changes to it. Checking in an object adds a new numbered version to the object history.