Problems with first install

I just tried to install grav core+admin, to a debian buster server, with apache 2.4., and the strangest thing happens.
I download it to my webroot (in my case /var/www/html, unzip it and it doesn’t appear online. Everything else in the folder is present. Just not grav.
Imagining that it could be, somehow, linked to not having activated the admin module, I tried to do that, but it told me it couldn’t find bin/gpm.
This is so weird, I am sure I’m missing something terribly obvious, but I don’t know what.
I’m rather new to using a server and am just now trying to use cms, so it is probable that I’m missing something basic.
If anyone could tell me what it could be, it would be great.

Thanks in advance for all the help given.

Possible permission issues for both owners and folders?