If you get a 404 when accessing adyen.min.js after activating JS minification in Magento 2 you can solve this by adding a JS minification exclusion. You have to create/update the configuration value for the
dev/js/minify_exclude path to include the URL or a pattern of the URL.
INSERT INTO core_config_data (scope, scope_id, path, value) VALUES ('default', 0, 'dev/js/minify_exclude', 'adyen.com/checkoutshopper');
This SQL query could override a previous configuration if you have one, so you should check if it needs to be updated instead.