How can I get a free SSL certificate to install it in my ubuntu VPS?

Letsencrypt is the standard now to where there's little point paying for an SSL cert. Back in the day the only free offerings were terrible affairs that were only recognised as valid in half the browsers out there - fortunately those days are long gone.

I'd be questioning why your host doesn't have certbot preinstalled.

@C0D4 Examples of such web hosting sites?

@C0D4 because it's a vps, not a webhost. I'd be pissed if my host started including software that isn't pre-installed in the os, without any major reasoning.

@Kimmax you strapped a domain to it, that seems reason enough.

@C0D4 You telling me you want another entity fucking around with YOUR system, that's under YOUR control, just because some outside factor might suggest you want to do a specific thing with it? Because I linked a fqdn? The name literally says VPS. Virtual PRIVATE Server.

@C0D4 We can argue if you install from a pre-built LAMP stack or something. But just because? No way.