Hi,
For the drafts and submission component to show up in the component browser, you need to follow below steps -
1) Select design mode and then select the drafts and submission component (Document Services component group) as shown in the below screenshot:

2) Now, go back to edit mode and you'll be able to the drafts and submission component in the component browser as shown in the below screenshot:

We hope this helps!
Regards,
TechAspect Solutions