Navigate to Policies–>New Policy–>New Blank Policy. Kindly do the configurations as per your requirements.
After configuring, please navigate to Policy Targets–>Domains. You can see your domains listed here.
For any domain, click on the arrow next to it to expand. Here, you can select multiple OUs or the entire domain. After selection, click on OK.
Next, select User Groups. Click on +Add User Group. You can see all your AD user groups listed here. Select the desired user groups and click on OK.
Save the policy and it will be active on the devices you have selected.
Please use the help link for a detailed explanation.