Condo association changes locks after assessment default

My condo association (HOA) is charging a "special assessment" this year. (The second in 8 years.) They sent a letter at the beginning of the year telling us we could make a discounted lump sum payment, or make payments each month. The total (without discount) is due at the end of this year.

I sent them a letter to tell them I have been unemployed for 2 years, and cannot pay monthly, but hopefully will have a job this year, and pay the total by the end of the year. They have changed the locks on the clubhouse and pool, and were distributing the keys today at the yearly "voting for new members" meeting. I went to get my key, and was denied because they say I'm behind in my fees. I am paid to date in the fees, but not the new assessment.

Can they do this? Deny giving me the new key to the pool, which I had access until they decided to spend money on changing the locks, which they have done twice in the last 8 years. Does this mean I don't need to pay the assessment unless I want pool access? I was unaware of this "rule" until I went to get my key. This is in Indiana. Is it legal?