Raspbian is more Debian than Ubuntu. The instructions are for Ubuntu, you’ll have to adjust Ubuntu specific commands to Debian.
In this case, I think raspbian will install PHP 7.3, which is the recommended PHP version for ownCloud by default anyway. So you don’t need to add an additional repository to install an alternate PHP version on your operating system and you should be able to omit these commands.
Hello, i tried without this part and it worked.
At the moment i went till adding the trusted domain.
I added my local PC ip adress. Sadly the owncloud only start with the trusted_domain issue.