The URL seems to be incorrect.
1) Go to https://experiencecloud.adobe.com/
2) Go to Launch
3) Select your already existing Property.
4) Then, go to Environments tab.
5) Click on box button beneath the Install column to open the instructions.
6) Copy the src attribute's value () & paste it in your configuration on AEM side( Tools -> Cloud Services -> Adobe Launch Configuration -> Properties). Do the same for all your environments in the configuration.
7) Then, publish this config, open the site in new browser & verify whether you no longer see 404 for the launch.min.js file.
Hope it works for you.

