How to type the @ sign in a web browser from a Spanish keyboard
Solution 1:
AltGr 2 for International Spanish.
AltGr Q for South American Spanish.
Source: https://answers.microsoft.com/en-us/windows/forum/all/where-is-the-at-sign-on-the-spanish-keyboard/babccecd-d692-422b-962f-026a47a64a65