Indesign doesn't open PageMaker files (PageMaker 6.0-7.x publications and templates).
Open the PageMaker files in Indesign CS6 or an earlier version first, and then save them to native Indesign Format (.indd ). Once the files are saved in InDesign format, Indesign can open the files.
To know about Pagemaker settings support in Indesign CS6 and earlier versions, see the following document: Open PageMaker files.
Indesign does not support opening PageMaker files.