I am using Fastreport 5.3.
Build and install fs_lazarus.lpk package in the Fastscript folder.
Build and install fr5_lazarus.lpk package in the Source folder.
It shouldn't be trying to find anything related to Delphi or QR unit unless you are trying to use Delphi packages.
If you are still getting errrors when installing, post what they are so someone might help you.