I was just told by my employers wc insurance claims adjuster that if I don''t accept their settlement offer I MUST have an attorney. Is this true?

What the insurance adjuster is saying to you is that she has reached her last and best offer. The adjuster is asking you to obtain an attorney to move your claim forward.  The attorney could review the offer and advise on the next best step.  The max fee for an attorney in Illinois is 20% of whatever is disputed or an agreed percentage over your prior offer.  You do not need an attorney and you could try handling this yourself. However this may not be in your best interest to try this yourself and with a final settlement offer already being made you have very little downside in consulting a lawyer.  Many lawyers who regularly practices workers compensation law will provide you a free consultation by telephone.  In light of sweeping changes that occurred with worker's compensation in this State following 9/1/11 law enactments you should at least consult with an attorney.  Accordingly, you must not have a lawyer and can proceed to a litigate this matter on your own but this is customarily not advisable.