the Uno should work fine (mine is currently running on an Uno; I replaced the Nano). the rtc ds3231 should work too, but there may have to be minor tweaks in the code. Not sure.
Can you post the error message? I bet it has something to do with the library. Might be something related to the RTC library which I might have to fix. try changing:dayOfTheWeek() to dayOfWeek()? (or possibly vice versa)
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