Dual boot Linux Lite and Prime OS

[pkmaarsen]

Hi.
Trying to install Android Prime OS next to Linux Lite. Standard installation like with Lubuntu, MX Linux, etc. was relatively simple. When I tried this method with Prime OS, theGrub menu did not show Linux Lite.
Therefore I followed https://brothersithub.blogspot.com/2020/...buntu.html
Thus I installed Prime OS in the Linux Lite System folder / directory of Linux Lite.
To make a boot menu, I opened Grub Customizer, created a new Configuration with the name Prime OS.
Everything looked OK. I rebooted and went to the Grub Menu, where I found Prime OS next to Linux Lite 5.4 After choosing Prime OS, the answer was: '/primeos/kernel' not found.

Furthermore, I got the following message:
===========================
Install Updates Error log
===========================
Install Updates could not fetch the package cache information lists.
Go to https://www.linuxliteos.com/forums/ and paste the log below into a new or existing thread for assistance.

============ Log ===========

Hit:1 http://archive.canonical.com/ubuntu focal InRelease
Ign:2 http://ppa.launchpad.net/danielrichter20...zer/ubuntu focal InRelease
Err:3 http://ppa.launchpad.net/danielrichter20...zer/ubuntu focal Release
  404  Not Found [IP: 91.189.95.85 80]
Hit:4 http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit:5 http://repo.linuxliteos.com/linuxlite emerald InRelease
Hit:6 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:7 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease
Hit:8 http://security.ubuntu.com/ubuntu focal-security InRelease
Reading package lists...
E: The repository 'http://ppa.launchpad.net/danielrichter2007/grub-customizer/ubuntu focal Release' does not have a Release file.

So my question is: can someone please help me out?
Thank you forum!  Paul