We use Git LFS to keep track of large files, so you must install the Git LFS extension before you can commit/push code to the repo. Once Git LFS is installed on your machine (and you restart your terminal emulator), you don't need to do anything else; just commit and push as usual.
Then, import the project into Unity 2018.2.14.
Before you commit and push, make sure you're committing the correct
changes to the repo (run git status before you git add and after you git commit).