I ran into a similar error. Did you, like me, perhaps install neovim from the package manager (apt)? If so, this version of neovim is too old :(

If you return to the NvChad installation instructions, click the link to Neovim 0.10 and install it manually. I opted to install the 0.11 release from the neovim release page.

Be sure to delete your previous neovim and any nvim folders (like ~/.config/nvim) and try the install again from the top.

Hope this helps!