Post type archive not found

I’m not sure if I’m missing something obvious but I have created a custom post type called ‘resources’

I have created a testing post in this custom post type, and that displays great. As it should.

But if I go to localhost/resources/ I get a 404? I’m wanting to create an archive / splash page to showcase the various categories within the resources custom post type.

I have an archive.php file but still 404? I’m not very advanced with wordpress so maybe I’m missing something really obvious, appreciate any help.

Thank you.