Can't build on Ubuntu?

I tried to follow the instructions, using init with `make init NEXUS_REPO=false` but when I run the `make build` afterwards I get errors, and I can't proceed.

```
ls: cannot access '/home/ubuntu/uibuild/pcs-web-ui/build/static/css/main.*.css': No such file or directory
node:internal/modules/cjs/loader:1137
throw err;
^

Error: Cannot find module 'csso'
Require stack:
- /home/ubuntu/uibuild/pcs-web-ui/packages/app/.bin/minify-css.js
at Module._resolveFilename (node:internal/modules/cjs/loader:1134:15)
at Module._load (node:internal/modules/cjs/loader:975:27)
at Module.require (node:internal/modules/cjs/loader:1225:19)
at require (node:internal/modules/helpers:177:18)
at Object. (/home/ubuntu/uibuild/pcs-web-ui/packages/app/.bin/minify-css.js:3:18)
at Module._compile (node:internal/modules/cjs/loader:1356:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1414:10)
at Module.load (node:internal/modules/cjs/loader:1197:32)
at Module._load (node:internal/modules/cjs/loader:1013:12)
at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:128:12) {
code: 'MODULE_NOT_FOUND',
requireStack: [ '/home/ubuntu/uibuild/pcs-web-ui/packages/app/.bin/minify-css.js' ]
}

Node.js v18.19.1
Assets compiled.
ls: cannot access '/home/ubuntu/uibuild/pcs-web-ui/build/static/css/main.*.css': No such file or directory
ls: cannot access '/home/ubuntu/uibuild/pcs-web-ui/build/static/js/main.*.js': No such file or directory
Compiled assets injected to html page.
Adapting for standalone usage.
rm: cannot remove '/home/ubuntu/uibuild/pcs-web-ui/build/static/js/adapterCockpit.js': No such file or directory
Adapted for environment
Prefixed asset paths: '/ui'.

Environment adapter minimized
Marks prepared
rm: cannot remove '/home/ubuntu/uibuild/pcs-web-ui/packages/app/node_modules': No such file or directory

/home/ubuntu/uibuild/pcs-web-ui/build/static/js/adapter.js: 1109
```

Please advise. I don't know what a nexus repo certificate is.