"Your Apple ID cannot end in @icloud.com. Choose a different email address"

Hi eugene37,

Thanks for reaching out to Apple Support Communities. It sounds like you're having an issue with creating an Apple ID. We're happy to assist.

Are you looking to create a new Apple ID? If so, we recommend following the steps here: How to create a new Apple ID

Additionally, "If you set up iCloud using an Apple ID that doesn’t end with @icloud.com, you must create an @icloud.com email address on your iPhone, iPad, iPod touch, or Mac before you can use iCloud Mail." You can find that information and helpful steps here: Create an email address for iCloud Mail

If you've already established an Apple ID and are just looking to change it, we recommend checking out the steps in the section "If you can't change your Apple ID" from the article here: Change your Apple ID

Best!