Your Ruby version is 2.7.0, but your Gemfile specified 2.6.3

Why is a Gemfile being created what specifies 2.6.3? How do I make it create a Gemfile that specifies 2.7.0???

Thank you

How do I change my Gemfile version?

Process: install the gem generically, looking up your target version on rubygems.org, then update and version your Gemfile. the install command is in the right-hand column. then you can: gem install gem_name -v 1.5.

What is a Gemfile Ruby?

A Gemfile is a file that is created to describe the gem dependencies required to run a Ruby program. A Gemfile should always be placed in the root of the project directory.

Just change: ruby '2.6.3' to ruby '2.7.0' in your Gemfile and run bundler install in your terminal. Gemfile is just a manifest that contains gems and ruby version that must be installed in current folder. Here's some info about Gemfile on bundler doc.