IL does not participate with Nursys. Once you file your application for Licensure by Endorsement in Indiana, you will have to contact the IL Dept. of Professional Regulation to request that they provide the Indiana Board of Nursing with the necessary information (graduation from an approved school of nursing, NCLEX scores, license history, etc.). There is a fee for this, which you must pay before your request will be processed. IL is notoriously slow in addressing these requests, so be prepared for several weeks' wait.
Once your Indiana license is issued, you will be the holder of 2 licenses. A very wise nursing insturctor advised my class to always keep our original nursing license current, unless we absolutely couldn't afford to do so, or were certain that we were ready to retire from the profession. The reason being that any time you move, decide to practice across state lines, or consider a tele-health position, and need an out-of-state license, the original state of licensure must provide the necessary information to the new state. They are much more diligent in doing so for current license-holders than those with inactive or lapsed licenses. IL is an excellent example of this. The state does not participate in the nursing compact, nor seems inclined to do so in the future, so you may find yourself needing to apply for multiple out-of-state licenses over your career.
Always keep your state boards of nursing current with your address so that you receive renewal notices. If you decide not to maintain a license that you don't anticipate using, formally place it on inactive status, rather than simply letting it lapse, which can cost you dearly if you subsequently need to re-new that license in the future.
Good luck with your job!