Mail isn’t working

So I have the IPhone 15 and It’s updated to IOS 18.1, yet for some reason after 3 days of trying to make this work, my mail isn’t going into the app; it’s only going into the iCloud mail website. I’ve went through the troubleshooting and help steps multiple times now and it’s still not working. It’s genuinely aggravating and it’s making me think that apple just simply doesn’t work and has become sub-par in certain areas.