I am unable to install ZENphoto. All rights are good. Maps 775 and files 664.
Browser wants to open an app. But I don't get any install capabilities.

My website is running at One.com. PHP Version 7.1

What can I do wrong?

Please try the support build from Github. This is a bug.

I have solved it through Zp-core/setup/index.php.
And now it works.

You mean you hacked the file? ;-)

Yep, it seems like that. But it works:-)

Sure ;-)