It needs to be editable in HD2021. The article I linked in my post provide the location of the settings that need to be changed. Below is the copied text from the linked article.
https://www.chiefarchitect.com/support/article/KB-00516/sharing-a-plan-file-with-a-home-designer-user.html
To allow editing in Home Designer
If a Chief Architect user wants to be able to send a Home Designer user a file, first check to make sure that the versions that both users have are compatible. If the versions are compatible, then, the Chief Architect user needs to allow for editing in the Home Designer programs before sending the file.
Click Edit> Default Settings , and in the Default Settings dialog, click on Plan, then click the Edit button.
In the General Plan Defaults dialog that displays, check the Allow Editing in Select Home Designer Products box.