To approve absence request as Authorizer or booking request as Manager from your mobile, go to menu and press Manage Requests. First tab displays absence requests.
Manage absence requests in Astrow Mobile
Second tab displays booking requests:
Manage booking requests in Astrow Mobile
You can approve or reject the requests and add comments:
Manage requests approving/rejecting comment in Astrow Mobile
and press Manage Requests. First tab displays absence requests. 
or reject 
the requests and add comments: