Error: error converting “.git” to absolute: Access is denied

When installing and running a runner on Windows with non-admin account (a domain user), getting the following error:

git-lfs/2.12.1 (GitHub; windows amd64; go 1.14.10; git 85b28e06)
Error: error converting “.git” to absolute: Access is denied.
Not in a git repository.

The source code has been cloned from the repository, so git commands do work.
GitLab runner version 13.8.0, Windows Server 2019.

Which permissions does GitLab runner need?