ESXi free is an iso file that you can download from VMware (ok, suppose their website designer was formerly at HP and formerly at IBM, simply producing chaos everywhere......). If you still have a CD/DVD drive (or external USB), you can simply burn the iso to a CDR and boot
Rufus is a tool to use an iso to create a bootable USB stick from it
https://rufus.ie/
Last time that I have tried NextCloud, I have simply deployed the .ova in ESXi
(but avoid NextCloud now in favour of Amazon S3 compatible sharing of a ZFS filesystem, much faster and simpler directly in OmniOS)
see https://www.hanssonit.se/nextcloud-vm/
Rufus is a tool to use an iso to create a bootable USB stick from it
https://rufus.ie/
Last time that I have tried NextCloud, I have simply deployed the .ova in ESXi
(but avoid NextCloud now in favour of Amazon S3 compatible sharing of a ZFS filesystem, much faster and simpler directly in OmniOS)
see https://www.hanssonit.se/nextcloud-vm/