The button to submit flag strings is not active on the hackthebox site

Hello everyone,
I rented the PRO LAB: DANTE and found the first flag.
my problem is that even if I am connected correctly to the VPN, the section to submit the flag string is not active.
Hope someone can help me.

I am correctly connected to the vpn

What do you mean, the button is not active?
In the upper right corner there is a field “Input Flag Hash”.