FAR 15.506 doesn't apply, but that doesn't mean you don't have to debrief unsuccessful offerors when using SAP. Your evaluation factors for award drive your debriefing requirements when utilizing SAP. It's one of the few times where FAR 13 actually leads us to FAR 15 without us trying to invoke FAR 15 procedures.
FAR 13.106-3(d) Request for information. If a supplier requests information on an award that was based on factors other than price alone, a brief explanation of the basis for the contract award decision shall be provided (see 15.503(b)(2)).
FAR 15.503
(b) Postaward notices.
(1) Within 3 days after the date of contract award, the contracting officer shall provide written notification to each offeror whose proposal was in the competitive range but was not selected for award (10 U.S.C.2305(b)(5) and 41 U.S.C.3704) or had not been previously notified under paragraph (a) of this section. The notice shall include-
(i) The number of offerors solicited;
(ii) The number of proposals received;
(iii) The name and address of each offeror receiving an award;
(iv) The items, quantities, and any stated unit prices of each award. If the number of items or other factors makes listing any stated unit prices impracticable at that time, only the total contract price need be furnished in the notice. However, the items, quantities, and any stated unit prices of each award shall be made publicly available, upon request; and
(v) In general terms, the reason(s) the offeror’s proposal was not accepted, unless the price information in paragraph (b)(1)(iv) of this section readily reveals the reason. In no event shall an offeror’s cost breakdown, profit, overhead rates, trade secrets, manufacturing processes and techniques, or other confidential business information be disclosed to any other offeror.
(2) Upon request, the contracting officer shall furnish the information described in paragraph (b)(1) of this section to unsuccessful offerors in solicitations using simplified acquisition procedures in part 13.
As always, please be careful when trying to shoehorn FAR 15 procedures into your FAR 13 buys (I don't recommend incorporating FAR 15 procedures in a SAP buy...not at all).