Welcome to the community @Imen_Aguerbaoui
It looks like you are trying to connect as a unattended robot, when you probably just want to access Studio as an Automation Developer.
You might have installed UiPath incorrectly in the Install Wizard. Or you don’t have an Automation Developer (Pro) license.
Open Assistant and go to Preferences, and then try to sign into from there. It’s easier. Sign into your Orchestrator URL and it should fetch the correct license (if there is one available) and you should be sorted. If not, send a screenshot of you assistant and let’s take it from there.
I have assisted someone else before with the same issue on the forums, please refer to this thread:
First assign an unattended license to the machine in orchestartor from tenant → machines pages
then give robot role or automation user/developer role to the user
cheers