Where is the language about enrolling for electronic payments? The General T&Cs say "epayables" but are we addressing this in other documents?

Language regarding any expectation/requirement must be included in the solicitation. Supplier need to know at the time they submit their proposal what the conditions are. If accepting electronic payment (crd) is a requirement then they will develop their proposal based on that knowledge. The process of how a supplier enrolls is different and can be discussed following contract award.