The first time you open it, the list of entities for the current environment will be automatically loaded. You can also click the "Reload entity" button above to load the entity.

Select the entity for which you want to edit permissions.

After selecting the entity, click the "Load permissions" button above to load the permission information of all security roles in the environment for the selected entity.

Double-click the permission icon in the table, similar to permission editing in the Dynamics365 system. After editing, click the "Save" button to save the edit.

The current result can be saved to the desktop.

Select Entities as the target entity, and click Load permissions to load the target entity permissions, then select copyEntities as the copy entity permissions, and then click Copy From Entity to copy the permissions, this operation is not directly saved but will generate a processing list processLists, check that the copied permissions are correct, and then click Save Your Change.(Thanks for the @LYMDS enhancements.)