Unable to serve locally (activate_bin_path error)

[muygalan]

Preface: I am using Windows 10 and using WSL.

I cloned a new copy of the Mediumish theme following the instructions here.

I am receiving the following error(s):

First command bundle:

Traceback (most recent call last):
        2: from /usr/local/bin/bundle:23:in `<main>'
        1: from /usr/lib/ruby/2.5.0/rubygems.rb:308:in `activate_bin_path'
/usr/lib/ruby/2.5.0/rubygems.rb:289:in `find_spec_for_exe': can't find gem bundler (>= 0.a) with executable bundle (Gem::GemNotFoundException)

Second command jekyll serve --watch:

Traceback (most recent call last):
        5: from /usr/local/bin/jekyll:23:in `<main>'
        4: from /usr/local/bin/jekyll:23:in `load'
        3: from /var/lib/gems/2.5.0/gems/jekyll-3.8.6/exe/jekyll:11:in `<top (required)>'
        2: from /var/lib/gems/2.5.0/gems/jekyll-3.8.6/lib/jekyll/plugin_manager.rb:48:in `require_from_bundler'
        1: from /usr/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
/usr/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require': cannot load such file -- bundler (LoadError)

Any thoughts on what could be wrong?