Best Practices for Installing to use with Nextcloud

[koolandrew]

HI,

I would like to install with Nextcloud, and the documentation seems somewhat limited. I did find this post here, https://github.com/rotdrop/nextcloud-roundcube?tab=readme-ov-file#installation and it said  the following:
"Due to the technology used -- Roundcube just runs in an iframe -- there are some restrictions caused by the same origin policy which at least nowadays is widely in use.

In principle this boils down to the point that the Nextcloud server installation and the Roundcube installation must be served in the same DNS domain.
NC Domain equals RC Domain
In this case nothing special has to be done. The administrator can simply enter the location of the Roundcube installation in the adminstrator settings of the app."

I am a somewhat limited admin, and not 100% clear about this, as to install the roundcube server on the vm as the nextcloud. Or install it separately but use the same dns, i guess...but i am not sure then how it would be the same...for example i could use domain.cloud for nextcloud and mail.domain.cloud....