C rating still applies, charging at 1C is usually "fast" charging for most cells and that takes an hour, charging in 5 minutes is is 12C which is normally "bad", would need lots of active cooling.

50kw would take 2 hours on a 100kwh pack so it would only be 0.5C. To do it in 5 minutes would require 1.2 megawatts of charge rate.