Adding a new submodule to project - permissions issue

We are using Gitlab 15.11 on a stand-alone network. We currently have a large project with many submodules. I’ve had no problem making changes, uploading, downloading, etc. Today I needed to make a new submodule. I navigate to the roles dir, and issue this to create a new submodule:

git submodule add

Here is the error I get back:

fatal: Could not read from remote repository
Please make sure you have the correct access rights and the repository exists.
fatal: clone of ' into submodule path ‘/work/roles/newsubmodule failed’

Why am I not able to create the submodule? I have the correct permissions - I’ve tried this as a user and as root with no difference.