“git add” returning “fatal: outside repository” error

Question

First in the clone folder you can create a Branch (so the master stay untouched)

git branch [branch_name]

After, just copy the files you want from your old folder to the clone folder.

When you are done, just add / commit your change and Merge your branch into the “master” branch. It will look like to something like this:

git add .
git commit -m "Comments"
git checkout master
git merge [new_branch]

Try this tutorial from GitHub.