Install Issues with OS and Composer 2
I can see in your output that you are trying to update to a specific version of Composer and it also prompting an &quot;Access Denied&quot; shortly after:
PS C:\&gt; composer self-update 1.4.1
Upgrading to version 1.4.1 (stable channel).

Unable to write &quot;C:\ProgramData\ComposerSetup\bin\composer.phar&quot;. Access is denied.

So it looks like that command already failed. You may have to manually install Composer on your machine if you run in such permission errors and move the composer.phar executable to the appropriate directory.
PHP 7.3
Please also see this GitHub issue for the ErrorException that you are facing: PHP 7.3 breaks composer with continue/targeting error (solution: downgrade to 7.2) #7783

[ErrorException]
&quot;continue&quot; targeting switch is equivalent to &quot;break&quot;. Did you mean to use &quot;continue 2&quot;?

In that issue it states that you will need at least Composer version v1.6.0 or up to be compatible with PHP 7.3.
Composer v1
Is there any reason why you need an old v1.4.1 version? If not then for now I suggest you rollback to the latest stable version of Composer v1 as per @Kevin's comment, which you can do by running:
composer self-update --1

Which should currently give you Composer v1.10.17, or again if that fails download the latest v1 manually.