Is a separate enrollment required for mobile and desktop?

Yes. The typing pattern that is recorded from a physical keyboard cannot be compared to one from a digital keyboard (i.e., mobile devices with a touchscreen) even if they are coming from the same user. 

We need to treat the enrollment process differently according to the used device type. 

For desktop (i.e., physical keyboards), the typing behavior is similar between devices as long as the keyboard layout remains consistent.

For mobile, it is important to consider how the user holds the device (i.e., the “mobile position”) since this impacts the typing behavior. Therefore, each position should be enrolled separately. For more information on mobile enrollment, check out the API documentation