LOC (Letter of Credit) Billing in Grants?

Summary

Would like to know how this functionality works and what are the necessary steps to make it work.

Content

Can anyone please advise how the Letter of Credit Billing in Grants works and what are the set up steps
to make it work.
I tried creating an Award Template and enable Letter of Credit Billing. However, it is grayed out and I am not able to enable it and proceed any further. Are there any prerequisite setup steps I am missing?

Any help appreciated.

Thanks and regards

--Paul