Hmm this should just work, it's not a pop-up, and theres nothing fancy going on. Questionable.
Is there anything abnormal about your setup?
The reason you can't just enter your Steam ID in a field somewhere is that by logging in you verify that it is in fact your Steam ID (aka that you have the login information), and this prevents abuse (no wrong bans etc)
This process isn't meant to be and shouldn't be sidestepped.
Verify that:
You aren't using a VPN
You can access and login to steampowered.com
You are using Chrome
You are not on mobile
Your computer isn't infected by malware (redirect intercepts)
You are logged in on this website
You don't have cookies disabled
You don't have JavaScript disabled