[NSFW] password protection

Hello folks.
I’m running into an annoying problem here:
I have a number of GT3 galleries that are not intended for the general public and I have provided them with a password.
To my surprise this doesn’t work at all? Anyone can just enter it, but, and that is absurd, is the box where the password must be entered at the bottom of the opened page? And that can, given the galleries, partly because of their content, be intended for specific customers.
So the question: why is this not working properly?
I am building my website with with Twenty Twenty-one theme from wordpress.
WARNING: IF YOU ARE OFFENDED BY NUDITY DO NOT SURF TO THAT PAGE.
THX
Johny

The page I need help with: [log in to see the link]