Enable Decrypt Order Button/Action
Below are the steps required to enable the decrypt order button on the action item page of your environment.
Add Custom Permission
To gain access to the Decrypt Order button, you will need to assign a custom permission to the permission set of your choice.
The name of the required custom permission is 'i42as.Decrypt Order'.
To learn about how to set customer permissions, go to https://help.salesforce.com/articleView?id=custom_perms_overview.htm&type=5 for more info.
Change Action Item Layout
To enable the Decrypt Order button, you will need to modify your Action object page layout. Add the 'Decrypted Order' lightning action to your list of actions and save.
Once the two steps above are completed, the button should be visible and upon clicking you should see the order information decrypted inside a modal.