'linkedin jail' means you have had a restriction on your account because of an increase in activity. If you had reached out to a significant number of people on linkedin and this has triggered the response you have given. If you are seeing this message, it means that LinkedIn has determined that you are not following the LinkedIn guidelines.
As the message states, you can't be on LinkedIn if you're not following the guidelines. The only way to get around this is to deactivate your account.
How to deactivate your LinkedIn account
LinkedIn allows you to deactivate your account if you are unable to log in.
If you don't want to deactivate your account because you have a lot of contacts, you can choose to block your account.