This puzzle requires the “Killing Floor” spec record.
There is only one path through the floor grid that follows all the rules the whole time. The correct path starts with the blue G.
After finding the correct path, only some of the letters along the route are important.
It’s important to remember that Dr. T’ana designed this protocol to blast you every third step you take.
Taking note of the letters on each step that you get blasted will give 9 letters that spell out the answer.
ANSWER REVEAL: The correct path across the floor goes G, S, I, L, B, N, T, E, C, E, A, O, L, A, G, H, L, N, F, N, I, T, W, T, D, H, O. Taking note of every third letter spells out INCOGNITO. Looking at the “medical cross target” envelope, incognito is synonymous with COVERT. So COVERT is the keyword that grants access to the envelope.