When you choose ‘Direct Dial’ from the IVR it does not mean that a caller will be able to direct dial a ringgroup or queue in the same manner that you can from an internal extension. Choosing ‘Direct Dial’ simply results in the local extensions (and their followmes) being included within the IVR context, nothing more.
If you want to include ringgroups, queues, or anything else - you need to make explicit options in the IVR and point the destination appropriately. You can use the same ‘ringgroup number’ (or equivalent) as the dial option, or any other number - and then choose the destination for that option accordingly. This is how you expose such destinations within an IVR.