Cant install theme on Jekyll 4.0.0 version


First time trying Jekyll. I have Windows 10 Home. Installed Ruby (2.6), Jekyll (4.0.0) and Bundler (2.0.2). And everything works fine (I go to the site through the localhost:4000 address).

But I encountered a problem when installing the theme in Jekyll. I liked the Sleek theme:

And I go to the Gemfile, write gem “jekyll-sleek” and in the terminal the bundler install command.

After that I get the inscription: Bundler could not find compatible versions for gem “jekyll”. Am I having compatibility issues? Jekyll version 4 does not work with the Bundler or what?

I am new to Jekyll. I worked with Wordpress for 5 years, sorry for the stupid questions and bad English.

P.s. Here is a screenshot of Power Shell:

The issue is that jekyll-sleek is not compatible with Jekyll 4.0.
The jekyll ~> 3.6 line in the link you posted is equivalent to
gem "jekyll, ">= 3.6.0", "< 4.0.0"

The solution is to edit your Gemfile to the following:

gem "jekyll", "~> 3.6"

Then run bundle install again.

Thank you for the answer!

When I write the following code:

gem "jekyll", "~> 3.6"

After I should run bundle install command? Or first I should do command bundle exec jekyll serve for website generation again?

Sry for bad English.

First edit the Gemfile.
Then run bundle install (Required only once)
Once everything has installed successfully, run bundle exec jekyll serve

Any changes to your source files will be automatically picked up by the server. The only exception to this is editing the config file. Each time the config file is edited, you’ll have to stop and restart the server.