@Taabott01 There won't be a direct option to log in with your Nintendo account, sorry for the confusion.
The linking process would need to be done on the Switch itself. In some cases the error you're seeing can appear if you haven't logged into the actual EA Account recently, so you would want to try logging into the website with your actual EA Account info normally first.
After logging back in with your normal EA Account information you'd then try restarting your Switch to see if that lets you continue with the link.
If not, reaching out to an advisor with the steps on that page would be best so they can take a closer look at the EA Account and see if there's anything else preventing that from linking properly.