Go back to your friend's computer. select all the files in Library, and go to Metadata > Save metadata to files (Ctrl+S)
All the editing is now saved to the files, you can now import them into LR5, and the edits will carry over.
You will not see the edits in the History panel, but all the sliders will be in the right place.
Note than any new features in LR6 that were used will not show in LR5.
If these files are proprietary raw files (like nef or cr2), the metatdata will be written to sidecar files (xmp) nex to the image files.
You will need to copy these over as well.
If it is any other file type, got to Edit > Catalog settings on your fiend's computer and check Include Develop settings ......
Do this before selecting the files and saving the metadata.