While printing an InDesign document as a PostScript file, the options to customize page are disabled.
This issue occurs if you have selected Device Independent as the PPD. Select Adobe PDF from the PPD list to resolve this issue.
If Adobe PDF is not listed under PPD, follow the steps below to have Adobe PDF as an option in the PPD list. The Acrobat 9 PPD supports custom page sizes, which are often necessary when using this workflow with the Print Booklet feature in InDesign.
Navigate to /Applications/Adobe InDesign CC 2018/Presets/.
Create a folder named PPDs. The folder name is case sensitive.
Download the PPD from the link below.
Extract the ADPDF9.PPD from the downloaded zip file and place it into the PPDs folder created in step 3.
Launch InDesign and select Adobe PDF from the PPD list.
The options to customize page are now enabled.