I'd have to strongly suggest finding another hosting provider and then choosing Ubuntu 20.04. All reputable providers will have this.
If that is not an option, then I'd ask this provider why newer operating systems are not available for install, and see if they'll install Ubuntu 20.04 for you.
If that doesn't work and you really really cannot change providers, I'd suggest choosing "Ubuntu 16.04 - minimal" from that list and then try to dist upgrade up to 20.04