@vjvanjungg yep, they use minified version of Ubuntu, so first of all you have to use their Ubuntu images to install a full version, see https://forum.cloudron.io/topic/10097/cloudron-install-error-dpkg-error/6?_=1696615795636
Also, I asked them about this on Twitter and they said:
I expect the Cloudron install script to work if you run the command "chattr -i /etc/resolv.conf" before starting it
https://twitter.com/netcup/status/1735265955364720757
So perhaps try that first and let us know if it does indeed work?