Problems compiling rocket chat from source on Ubuntu 18 and 20

I tried following the instructions: https://developer.rocket.chat/rocket.chat/rocket-chat-environment-setup/linux
These instructions seem to be very old, but I tried nevertheless.
Fre things I encountered:

• I cannot just run npm install yarn -g because npm doesnt come installed on Ubuntu, so I must install it first.
• After installing yarn with the command above, I get this:

> yarn@1.22.19 preinstall /usr/local/lib/node_modules/yarn
> :; (node ./preinstall.js > /dev/null 2>&1 || true)

/usr/local/bin/yarn -> /usr/local/lib/node_modules/yarn/bin/yarn.js
/usr/local/bin/yarnpkg -> /usr/local/lib/node_modules/yarn/bin/yarn.js
+ yarn@1.22.19
added 1 package in 2.226s

And as soon as I run "yarn" inside ~/Rocket.chat I get:

internal/modules/cjs/loader.js:638
    throw err;
    ^

Error: Cannot find module 'worker_threads'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at /home/manuelm/Rocket.Chat/.yarn/releases/yarn-3.2.2.cjs:423:2642
    at Object.<anonymous> (/home/manuelm/Rocket.Chat/.yarn/releases/yarn-3.2.2.cjs:738:8846)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)

Then I m stuck, I tried running yarn with sudo etc,, same thing.

Thanks for the help.

Start with the Linux environment setup documentation at developer.rocket.chat/rocket.chat/rocket-chat-environment-setup/linux and compare it with the reported Ubuntu 18/20 commands and the repository's Yarn setup. Reproduce the worker_threads error from the repository root, then define the supported prerequisites and update the instructions so a clean setup can be verified.