Regarding your question I would like to let you know that the easiest way to achieve this is to use a workflow like this:
Execute the PDF Splitter task to split the PDF file.
Execute the Set Job Infos and Variables task to extract the value (*).
Execute the Send to Folder task to save the split PDF file in an output folder and to use extracted value as filename for the split PDF file.
(*) You can execute the following steps to extract a value from the content of a split PDF file by the Set Job Infos and Variables task:
Insert the Set Job Infos and Variables task in a Workflow process in which you’ve already inserted the PDF Splitter task.
Select a Job Info or Variable (to which you would like to assign the value) in the Var/Info# column in the Properties window of the Set Job Infos and Variables task.
Execute the Workflow process in Debug mode step-by-step until the PDF Splitter task has been executed.
Open the Properties window of the Set Job Infos and Variables task by right clicking on the task and selecting the option Properties….
Click in the field in the Value column next to the already selected Job Info or Variable (in the Var/Info# column), right click and select the option Get Data Location.
Select the location in the Data Selector window and click on the OK button to apply and confirm the change and to close Data Selector window.
Click on the OK button to apply and confirm the change and to close the Properties window of the Set Job Infos and Variables task.
Please feel free to response if something is not yet clear to you or if you have any questions or comments.