I was able to get past this issue previously with the block producer server but I am drawing a blank for the relay1 server that I am creating from the beginning. It seems to fail soon after git checkout tags. I appreciate any assistance.
It turns out to be a directory issue. Make sure you are installing each step in the correct directory. It is very easy to get confused.
I ran into this same issue and found a solution from this post Problem installing Sodium package in R on an Ubuntu system - Stack Overflow
Basically all I did was run
sudo apt install libsodium-dev
and then re-ran “cabal build”