The 50th percentile is the median average. So he needs to be within 20% of the average wage of the top 30 earners at each club. So, if the median was 100k, he'd need to be earning at least 80k. If it were 50k, he'd need 40k.
I think :)
Zambia were in a similar position when they won it in 2012. The win lifted them 25 places. In the same tournament in a good run from Gabon moved them up 41 positions.