Hi,
I'm attempting the following module, where you need to install an unmanaged package.
https://trailhead.salesforce.com/modules/lightning_app_builder/units/lightning_app_builder_custom_comps 
I have followed the following help article's steps exactly
https://force.desk.com/customer/portal/articles/2710899-installing-a-package-or-app-to-complete-a-trailhead-challenge?b_id=13478

However, the unmanaged package is still being installed to my overall Salesforce instance, NOT to my "Trailhead Playground".

Given the challenge checks against the Playground, it is impossible currently to complete the challenge.
Is this a common problem & if so how do I solve it?
Thanks,
Matt