DDR3L RAM will work fine in your system. DDR3L RAM is dual voltage and will work in a system that was designed for DDR3. In this case Crucial is spot on. As for Windows 11, no your system is not Windows 11 compatible. You have a 4th generation CPU and Windows 11 require a gen 8 CPU or newer. And no your system cannot be upgraded to an 8th gen CPU.
Good day, Could you kindly assist. I have a dell optiplex 3020 and I want to upgrade. I am running an Intel core i5-4570 3.20ghz with 2x 4gb sdram. I want to upgrade my ram and I currently bought a 16gb 8500 ddr3l ram. Dell says optiplex 3020 doesn't support ddr3l ram and yet crucial (Dell partner) has listed ddr3l ram as supported on the Dell optiplx 3020. Please advise if I can still slot it in as I haven't done so.  2nd. Can I run windows 11 . Windows 10 has to many background process (e.gservice hosts)running that use up alot of memory. Your assistance is highly appreciated  Regards, 
Dell ram upgrade