Facing an error while installing npm for neovim coc

I have installed coc.nvim and am now installing the dependencies. To do this I need to install npm. The command I'm using to install npm is sudo apt-get install npm. However, I get this error when installing it:

Ign:1 http://archive.ubuntu.com/ubuntu  focal-updates/main amd64 linux-libc-dev amd64 5.4.0-90.101
Err:1 http://security.ubuntu.com/ubuntu  focal-updates/main amd64 linux-libc-dev amd64 5.4.0-90.101
  404  Not Found [IP: 91.189.88.142 80]
E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/l/linux/linux-libc-dev_5.4.0-90.101_amd64.deb   404  Not Found [IP: 91.189.88.142 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

I have tried running apt-get update but I keep getting this error:

E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied)
E: Unable to lock directory /var/lib/apt/lists/
W: Problem unlinking the file /var/cache/apt/pkgcache.bin - RemoveCaches (13: Permission denied)
W: Problem unlinking the file /var/cache/apt/srcpkgcache.bin - RemoveCaches (13: Permission denied)

How do I install npm?