The issue is likely with the aggressive timing (low latency) -- this RAM is designed for gaming systems that allow speed adjustments for memory.  Your system does not -- you'd be better off buying RAM tested and certified to work in your system:

https://www.crucial.com/compatible-upgrade-for/dell/latitude-14-(5480)

Thank you for your answer.

Interesting and strange at the same time.

The ram you suggested: 

DDR4 PC4-21300 • CL=19 • Dual Ranked • x8 based • Unbuffered • NON-ECC • DDR4-2666 • 1.2V • 2048Meg x 64 •

The one I have:

Kingston FURY Impact DDR4 2666MHz 32GB; 2x16GB, DDR4, 2666MHz, CL15 SODIMM 2666 MHz (PC4-21300)

Notice they have same Mhz and same type PC4-21300, whats the difference and why mine are not working? just curiosity at this point.

See the answer above  -- the cache latency is too aggressive for the system board.

The CL of the ram you suggested is 19, the one I have is 15 , how can it be more aggressive?