Sampling results in duplicating the input signal in the frequency domain. The Nyquist criterion specifies how you have to sample a signal from DC up to Fmax without aliasing. However, with the proper ADC, you can sample a signal from F1 to F2 where both F1 and F2 are higher than your sample rate. All you need to do is make sure that there won't be any signals below F1 or above F2 that will be aliased with the signal you want. This requires a bandpass filter instead of a low pass filter. The sample rate only determines the receive bandwidth, not the receive frequency range. This is called undersampling, and it is very common in radio receivers because it can eliminate one or more mixers and local oscillators.
In this case, it's also possible that they are using a mixer and LO to downconvert the input signal to a lower frequency for reception. Their block diagram is rather lacking.