EDIT: Success! The build completed and appears to be running well.
I am not completely clear on what my errors were but following the advice of @flamber I started from scratch and installed the latest for all of the necessary software. I hit a memory error with my 1GB droplet. I expanded to a 4GB droplet and the build completed without issue.
In case it is useful for anyone... These are the major steps I took that led to success.
- 
Created a new Digital Ocean droplet - 4 GB Memory / 25 GB Disk / NYC3 - Ubuntu 20.04 (LTS) x64 
- 
Upgraded GIT 
 A. https://git-scm.com/download/linux- add-apt-repository ppa:git-core/ppa
- apt update
- apt install git
- git --version
- git version 2.31.1
 
- 
Install latest JDK 
 A. Downloaded jdk from https://www.oracle.com/java/technologies/javase-jdk11-downloads.html
 B. pscp .\jdk-11.0.10_linux-x64_bin.rpm root@mydroplet:/root
 C. Followed https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-on-ubuntu-20-04
 D. java 11.0.10 2021-01-19 LTS
- 
Install leiningen 
 A. Followed https://purelyfunctional.tv/guide/how-to-install-clojure/#linux
 B. curl https://raw.githubusercontent.com/technomancy/leiningen/stable/bin/lein > lein
 C. These steps included the install of Clojure and the CLI tools.
- 
Install node.js 
 A. Followed https://www.digitalocean.com/community/tutorials/how-to-install-node-js-on-ubuntu-20-04
 B. Also referenced https://github.com/nodesource/distributions/blob/master/README.md
- 
Install yarn 
 A. Followed https://linuxize.com/post/how-to-install-yarn-on-ubuntu-20-04/
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git checkout release-x.39.x 
- 
bin/build