Those are likely to be 36x84 and not the 30x80 the closet door might be. You'll need the frame, too. All of my local Lowe's are showing 36x80 at about $200 (and needing drop shipping). If you go with a "security door" that will be a glorified storm door which will need hanging over the existing door which is complicated as the door likely swings out, not in, which is not the expected door swing for security doors. Also dropping a security door is once again screaming "break in here." Your house your choice. Me, I prefer that prying eyes look elsewhere and not scheme against my protections. Having bad people know to bring a three foot prybar or hooligan tool in advance, kind of obviates the protection. Ok, maybe you install one of these: https://www.lowes.com/pd/Gatehouse-Magnum-Black-Steel-Single-Door-Security-Door-Common-30-in-x-81-in-Actual-32-125-in-x-81-5-in/50374760 inside the closet, then, maybe. That assumes the closet, safe, etc. will clear the swing.