In most Nebraska DUI cases proof of financial responsibility is a condition of restoring the driving privilege, and it is also part of qualifying for an ignition interlock permit. Your DMV notice states the conditions for your case.
More detail
Nebraska handles driving under the influence under Neb. Rev. Stat. 60-6,196, and the DMV runs an administrative license revocation alongside the county court case. Because the two tracks are separate, the insurance step belongs to the DMV side and can be worked immediately rather than after the court date. That sequencing is worth acting on: where an interlock permit is available, the proof has to be on file before the permit issues, so a driver who starts the insurance conversation early can be driving legally weeks sooner than one who waits. What the filing does not do is affect the criminal case. It is a licensing condition, not a sentencing factor, and nothing about carrying it substitutes for the advice of a lawyer on the charge itself.