To modify folder permissions, in this instance the Aatrix folder, go to properties of the folder, security tab, Edit
To add the everyone group, click Add
Hit cancel when asked for credentials
Select the local server and hit OK
Type in everyone, hit check names, then hit OK.
If you aren't sure which groups/users are available you can select the Advanced button
Select Find Now, the system will give a list of the available users and groups that can be selected. You can double click the user/group you'd like, or click once to highlight and then OK to make your selection.
You will be taken back to the Select Users or Groups screen, select OK.
You can now modify the access permissions for the group as needed and hit OK when done.