Not sure if this is the solution, considering Google's search results getting worse these days but it gave me this when looking up that error code:
https://www.reddit.com/r/buildapc/comments/nvbhal/windows_10_install_fails_with_error_0xc0000005/ The tl;dr is when you run the Media Creation Tool, make sure to right click on it and select "Run as administrator"
Alternatively you could download the ISO and use
Rufus to create the USB installer.
EDIT: On a side note about how many sticks of RAM you have installed, the number shouldn't matter. While yes, there's potential for instability with more sticks, this can be mitigated by lowering the transfer rate of the RAM. And it also depends on the topology of the slots; i.e., if they're daisy chained or T-topology.
But I don't think any of this matters as long as you're not above the specified transfer rate the spec sheet says. You can try and go above it, but going out of spec always brings about a risk of instability.