If you use the above link, it will automatically fill in your QuickSight account (iotspot) and move to the next page. Enter your email address and password and click Sign in.
If you are asked for your QuickSight account name first, then enter iotspot and then click Continue. On the next page, enter you email address and password and click Sign in.
The QuickSight account name is always iotspot. Do not use your email address here.
In QuickSight, your email address is used as the username.