In the meantime, you may be able to export the PDF from Affinity and then use an external application to add these 'fillable forms', however I have no personal experience doing this, so hopefully other forum members can offer recommendations!
In the meantime, you may be able to export the PDF from Affinity and then use an external application to add these 'fillable forms', however I have no personal experience doing this, so hopefully other forum members can offer recommendations!