If you see the following message:
"Due to company policy, you can not request for absence in future"
It means that your next absence year is not activated yet.
Please follow the steps below:
Go to Configuration → Absence types → select the absence type and click "Edit" → go to the Requesting tab.
From "Requesting is possible in" choose how long in advance employees can request time off and then "Save".
After changing the configuration, Calamari will automatically allow you to request time-off for the next year.
Remember that this configuration is related to one absence type. You should repeat the above steps for each absence type if you want this setting to be applicable for all absence types.