Today I tested the installation again on the fresh server, and I’m still stuck at the same build step.
Maybe because I’m running it on Ubuntu? Would that make a difference? I know apk isn’t a command on Ubuntu.
I ran sudo apt update && sudo apt install curl iproute2 iputils-ping less nano tree ca-certificates lsof outside of Ozone, and then deleted the RUN apk add curl iproute2 iputils less nano tree ca-certificates lsof --no-cache command from the dockerfiles. The installation proceeded without any errors after that.
(As a side note, the SSL cert installed successfully. Thank you. 
)