Hi,
Thank you for reaching out. The CriterionUserInterest is not applicable to the Search Campaign. Please refer to this Criteria Usage table for more information.
Thanks and regards,
Xiaoming, Google Ads API Team
Hi,
Thank you for reaching out. Could you please share the screenshot for where you add user interest for search campaigns in the Google Adwords UI?
Thanks and regards,
Xiaoming, Google Ads API Team