I scan the ThingMarx logo in mobile app and it shown me error,
please find below image.
Can you please check the status of your Experience Service? Whether it is active or turned-off..
Just an FYI, you can find the Experience Service URL under Studio Project Configuration -> Info Tab -> Experience Service field. Copy the URL, append the url which should like "https://<replace-with-url-in-ExperienceService-field>:2019/ExperienceService" or "https://<replace-with-url-in-ExperienceService-field>/ExperienceService". If it is active, it should prompt for User/password, validate with your credentials.