My question involves landlord-tenant law in the State of: California

I recently filled out an application to lease an apartment at a large apartment management company. After filling out the application, I paid their $21 application fee and waited. Two days later I received an email saying that they had approved me, but it wasn't until a week after that (today) that I got an email saying that I needed to pay a holding deposit. The leasing agent told me they were experiencing "technical difficulties" in their system which kept them from giving me the notification to pay the holding deposit until now, and that usually they send that email out at the same time as the approval notification. By the time this holding deposit notification came out, I had already decided to back out on renting the apartment, so I told them I was no longer interested. They are now trying to say that I owe them part of the holding deposit anyway for the week between them approving me and now since they had to "take it off the market".

I've done some research, and I've found that technically, had I paid the holding deposit, they would be legally allowed to keep a portion of it. However, having not actually paid the holding deposit, can they legally force me to pay it now? Washington explicitly states that a "receipt of holding deposit payment" is needed in order for them to legally withhold it, but I'm not sure if that also applies to California. That's pretty much the closest I was able to find to relevant information on the matter.

Thanks for taking the time to read this issue!