You can still install it like this https://my.<cloudron>/#/appstore/rocks.paperwork.cloudronapp . But note that it was last updated 3 years ago. I tried to build a new version with latest with PHP a year ago and the app was not even building anymore. They have been re-writing a new version for a couple of years now.

@girish Thank you for trying. It still was not working, similar message as before. i tried boosting the ram to 4096MB even but it still failed. Oh well.