Hi, Edmund thatch, I spent two weeks facing this same essue im my Windows 10 machine.
You need to use the Command Prompt that you are sure about the ruby and Rails versions.
Checking on the left black windows, You’ll see ruby version is 2.3.3p222
(which rails installer has installed). Together with it, the Rails version is 5.1.7
On the flip side, the left windows shows us Ruby version as 2.6.5p114
and Rails version as 126.96.36.199
As you might guess, there is not need to change the path variable neither hidden any path if you are on the correct Command Prompt.
[…] which I can’t install because they need version 2.4 and the rails installer only goes up to 2.3.3
Yes, this ruby installer just look at ruby 2.3.3, but you might specify another version. It is writen on that tutorial blog:
If you are working on Windows, you should also install the Ruby Installer Development Kit.
And on this last link, it is said:
If you don’t know what version to install and you’re getting started with Ruby, we recommend you use Ruby+Devkit 2.6.X (x64) installer.
Which I also have chosen. This is the reason I can use both Command Prompt.
After install the apropriated kit, you might face another error related to the Bundle.
It is so because Bundle will try to bundle some old gem versions. Which you can avoid installing the last bundle version too. But dont worry, the command line will tell you about it and the apropriated command to type.
Check on the official site of ruby gem the latest version of all gems installed automatically by rails. And change it (if necessary) on the GemFile created by rails after run the rails new blog. And then run bundle install.
If you have any doubt, please let me know.