Open a console window with administrator permission.

 

Grants read permission on the inetpub folder (and sub-folders / files) for the CMonline-AppPool-User:

icacls C:\inetpub /grant "IIS APPPOOL\DefaultAppPool":(OI)(CI)R

 

Grants read&execute permission on the FieldServiceClient folder (and sub-folders / files) for the FieldServiceClient-AppPool-User:

icacls C:\inetpub\DefaultAppPool /grant "IIS APPPOOL\DefaultAppPool":(OI)(CI)(RX)