I had 3 technical rounds followed by a managerial round, which took around 4 hours.

I got positive feedback. On the very next working day, she (the HR) asked me for all the documents and called for an HR discussion. She sent an email for the HR discussion without mentioning any timings.

After some time, when I called her for timing information, she didn't reply. The next day, she called me and told me we cannot send any offer right now because of the financial year-end. I know she gave an excuse, but this is not expected from a company like Ariba.

They simply wasted my time and left.

Without any preparation, you can crack the interview.