Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature currently requires accessing the site using the built-in Safari browser.
If you are still using CentOS 7.9, it's time to convert to Alma 8 with the free centos2alma tool by Plesk or Plesk Migrator. Please let us know your experiences or concerns in this thread: CentOS2Alma discussion
As you can see on Plesk lifecycle policy page https://cscontact.plesk.com/plesk-lifecycle/ Plesk 9.x is EOLed and not supported officially.
Consider to use modern Plesk version.