The cache description has an English section (also, I almost understand the above language, danish I think). Very similar to Swedish, which is my native. Anyway, the cache description says:
[ENG] This is a challenge cache. To be allowed to log the cache, you have to be FTF on all dates in the month. The cache is at the published coordinates
That combined with reading logs, makes me interpret as that you need 31 FTFs, one on the 1st, one on the 2nd ... 31st.
The GetFinds() method supports FTFs as well. So this is technically possible.