I don’t know what wrong with this my Snapchat anymore

You cannot use Snapchat on your iPhone. Snapchat has banned your device and will reject any attempt to log in with any Snapchat account. If Snapchat has decided to make the device ban permanent, you'll never be able to use Snapchat on this iPhone ever again.

Neither we fellow users, nor Apple banned your phone – or can unban it. Only Snapchat can unban your phone – if they feel like doing so.

Snapchat Support – I get an error message logging in to Snapchat

"Device banned: SS18, SS06, SS07 errors

If you're seeing an SS18 or SS06 error code when trying to log in or create a new account, this means Snapchat has banned the device you're using due to abuse or repeated violations of our Community Guidelines. This is a safety measure we take to protect the Snapchat community when we detect suspicious activity.

If you're seeing an SS07 error code when trying to log in, this means your device has been banned from logging into Snapchat because too many accounts have been associated with the device. 

If your device has been banned, Snapchat Support cannot unban it for you."

You can't. Snapchat have banned your phone. Click on the "Learn More Here" link and it will explain it.