Installing the license from the disc. Auto-translated

Hello everyone.
I'm having trouble installing the game from a disc. I bought a licensed disc in a store.
I installed Uplay for activation and activated the key... but during installation, the program starts downloading the game from the internet... and I live in a place where internet is very expensive, and downloading 17 GB is a very costly endeavor...
I need help with installing the game.

Yeah, the idea of releasing a disc version and then having players download the entire new distribution seems pointless. It would have made more sense to just sell digital keys. It seems like the disc contains a very raw version, and a day-one patch is required, but instead of a delta update, they're releasing a completely new distribution... it feels rushed, and it's unlikely that all the resources needed updating, like textures and music.
Another option is to bring/take your computer to a place with decent internet access. But it's better to wait; they promised a significant update this week, so you can download it then.
And if you switch Uplay settings to offline mode? After activation, the game might work offline; at least Heroes 6 could be played in that mode if there's absolutely no other way to download it.

I installed the sixth installment of the Heroes series from the disc using the same Uplay... there must be a solution.

This is a recurring issue with Steam. You need to somehow stop the download and specify a path on your disk for Steam to install from... I had a similar issue with King's Bounty: Warriors of the North. I don't remember the details myself, but I found an official guide: https://support.steampowered.com/kb_article.php?ref=5357-FSQM-0382&l=russian
Good luck!

What about the option for offline mode in Uplay?
When you enter Uplay, there's an asterisk in the upper right corner – it leads to the settings.
There, you can select the option to launch Uplay in offline mode. I can't say for sure if this works for launching Heroes 7, as I haven't tested it. But Heroes 6 could be launched, albeit without the Conflux and Dynasty features. Also, Heroes 6 could be launched completely without Uplay by creating a shortcut to the game's .exe file and adding the key in the properties path /offline. Something like this: in the shortcut properties, in the "Target" field, enter "C:\Program Files (x86)\Ubisoft\Might & Magic Heroes VI\Might & Magic Heroes VI.exe" /offline.