You should check with a manager or other person at the hotel. Iirc, the California Transient Occupancy Tax may require an agreement before the stay begins for the exemption to apply.
See:
https://www.flyertalk.com/forum/los-...ax-refund.html
https://sco.ca.gov/Files-ARD-Tax-Inf..._chapter13.pdf
https://www.santabarbaraca.gov/civic...x?BlobID=17425
https://ttc.lacounty.gov/tot/