The best thing and as per most recommendations is to put a memory with the same specs and capacity. Same maker is not that important.
I just replaced in my GL503VM both rams with 2xCrucial Ballistix Sport LT, 16GB, DDR4, 2400MHz, CL16, 1.2v and it works perfectly.
https://www.crucial.com/usa/en/bls16g4s240fsdYou will notice a big change when you put the second RAM and it will change to Dual-Channel.