Where to find a Microchip MCU's ADC AC characteristics?
The specs you show will be met over the valid range of sampling time and conversion clock speed.  You can look at those specs to find the maximum rate the A/D can be run at.  That's the upper frequency, if you do everything else right, at which the errors won't exceed what you show.

Put another way, they are specifying each sample as a independent event.  It's up to you how to string those together, within the limits of signal impedance, acquisition time, and conversion clock period.