Add a group Custom Attribute Statement in Okta.
Set the name to groups, and FlexDeploy will find the groups without any modification of the group name attribute, or if you change it, use the same value in FlexDeploy.
Set your filter as desired.
Salesforce.
Open your connected app (App Manager → find your app)
Click New under Custom Attributes
Set the key to groups then click Insert Field to add the $UserRole.Name.