Yes, as with all water based paints, it is necessary to seal knots in bare wood prior to painting. Any standard knotting solution is fine to use and should not affect the performance or application of Earthborn Eggshell No.17.
However, if you are unable or reluctant to use a knotting solution, you could heat the knots with a hot air blower until resin bleeds out of the wood. You would need to wipe down with a solvent such as methylated spirits before painting. Dependent on the wood, this may not be a permanent treatment.