Hello, I installed Alma 8.5 and when installing Virtualmin I got:
▣□□ Phase 1 of 3: Setup
[ERROR] Your OS is not currently supported by this installer.
[ERROR] You can probably run Virtualmin Professional on your system, anyway,
[ERROR] but you’ll have to install it using the manual installation process.
In your post here you said are not yet supported, I did not know 
The Installation Guides page says: https://www.virtualmin.com/documentation/installation/
Manual Installation - Installation of Virtualmin and related packages manually. This method is time-consuming, and requires a high level of technical experience. This is not recommended , except in cases where the automated installation is inappropriate or impossible.
I do not have “high level of technical experience” What can I do then? 