Pages 26-34 show how to. Yes you can install 1 PCIe/NVME M.2 such as the one you ask about. Memory is upgradeable to 32 gigs (2 x 16) DDR4-2400 SO-DIMM. The Manual is a bit off but this information is accurate.
Post back with any more questions and please accept as solution if this is the info you needed.
Your device does support X4 drives so you should be fine.
The guide shows that your system will support 16 Gb based on using 2 x8 GB memory. If your system shipped with 8Gb of memory it would either be one 8Gb memory module or 2 x4 Gb memory. Checking your system configuration should show you.
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