InDesign CC does not have the capability of opening Pagemaker 6 and 7 files, but InDesign CS6 does.
If you have a Creative Cloud subscription, you can also download InDesign CS6 at no charge using the Creative Cloud desktop app.
In the Creative Cloud app, go to the Apps list. Scroll down until you see the heading Filters & Versions. Choose Previous Versions. You can download CS6 from there.
Both versions can run on your computer at the same time.