Custom Triggers can only be set up for metaproperties of the Select type. The type Select2 is not supported.
Go to Settings > Taxonomy > Metaproperties management.
Click for the metaproperty that whose option should be the trigger for the action.
In the options overview, click the dependencies icon for the option that should trigger the action.
In the Custom triggers section, select the following:
Choose trigger - decide if you want the action to happen when the metaproperty option is selected or deselected.
Choose target - decide which other metaproperty option should be affected by the trigger.
Choose action - decide what should happen to the affected metaproperty.
select - the affected option should be selected. This selection is available for the watermark, downloadable, archive and limited options under Advanced rights.
deselect - the affected option should be deselected. This selection is available for the watermark, downloadable, archive and limited options under Advanced rights.
prefill - the affected metaproperty option should display a text or date. Select one of the available metaproperty options and enter the text or date the option needs to be prefilled with in the text box that appears at the bottom.
Use the month/day/year format when entering a date.
empty - the affected metaproperty option should be left empty and should not display a text. This selection is active for the Text, Longtext and Date metaproperties. You can use this action, if, for example, all other options display a text, but this particular option should not.
Select the plus icon to create the custom trigger.
Now, selecting the specified metaproperty will trigger an action. If you want to edit the trigger or the pre-filled text in the custom trigger, you need to delete the custom trigger and create a new one.