Clients getting into admin area

Hello,

when some of my clients log into member area, instead of being sent there, they are sent to admin area. Some of these clients’ accounts I manually created (I checked off admin bar option so that it doesn’t show + I set a subscriber role for them), others were created automatically after making a purchase (I use Czech plugin Simple Shop but it’s only used for protecting certain pages, login details are still created by WordPress).

When I tried to login with their login details, it sent me to member area, so I’m not sure why it works for me and not for them.

Do you have any idea why this is happening and what I can do to prevent it?

I’ll appreciate any advice.

Thank you,
Barbora

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