Codesys has rules pertaining to the POU group and Devices group and what they can and cannot contain.
The POUs grouping of items can not contain some hardware specific device objects that do not have portable code that can not or should not be compiled into a portable re-usable library module.
Alarming is one of those things Codesys will not allow and is the reason the tool bin does not show that tab and others that are not valid when working in the POUs section.
The Alarm visualization needs to be created in the Devices tree and not the POUs tree.
Once your Visualization is moved to the Devices group, the Toolbox changes.
If you still do not see the Alarms and you have your visualization in the devices group it may be turned off in the tab (tags list)