I have changed the server for vostok-zapad.kharkov.ua. Now it uses the cPanel on shared hositng and I cannot use the Certbot via the SSH further.
Could you explain how can I activate, validate, and issue the LE SSL to install it on cPanel? How can I obtain the Certificate (.crt file) and CA-bundle (.ca-bundle file) from LE?
The ideal solution is that your hosting provider has it already integrated as part of the shared hosting package, so you just need to go into cPanel and turn it on.
If they're not, then it depends on the hosting provider and exactly how much control they have given you through their hosting package. You may be able to make do with a client that integrates with the cPanel API, like the one @griffin is working on (though I think there may be others out there too, depending on how much access you have).
I built the CertSage ACME client specifically for shared hosting users (GoDaddy users for example) who do not have root access and want a really easy way to get their certificates. If you are interested, I can send you the instructions. Super simple to install and no command line needed to use.