You should have the Post Resource Update option in any version.
You should also see it at the top breadcrumb:
If you don't see this, then it suggests some other issue. Likely permissions.
For example, are you the resource author? Only resource authors can post resource updates. If you aren't the resource author, then as an Admin (if you have permission) you should be able to Reassign the resource to yourself then as long as you have permission you can post a resource update.