You can use the same methods as for other policy types. For example, list all users and their assigned application access policy via:
Get-CsOnlineUser | select DisplayName,UserPrincipalName,ApplicationAccessPolicy
Or, filter out just the users with specific policy assigned:
Get-CsOnlineUser -Filter {ApplicationAccessPolicy -eq "ASimplePolicy"} | select DisplayName,UserPrincipalName,ApplicationAccessPolicy