If the rotor/quarq crank has a 24mm spindle, you can install the crank directly.
If it's a 30mm spindle:
The bearings (and bottom bracket) of your old frame is likely compatible between the two (unless it's some outboard type that extends the entire width of the system too much). You can swap the bottom brackets and the only change thing you should need to make is remove 4mm worth of spacers as the bb90 is that much wider (90.5 vs 86.5mm).
If it's a 30mm spindle:
The bearings (and bottom bracket) of your old frame is likely compatible between the two (unless it's some outboard type that extends the entire width of the system too much). You can swap the bottom brackets and the only change thing you should need to make is remove 4mm worth of spacers as the bb90 is that much wider (90.5 vs 86.5mm).