Hi Leena, I don't know anything about Founders Space but I do work for an accelerator, Collider, which takes equity and charges for the programme. Let me explain our rationale - maybe it is similar to Founders' Space.
We feel that there are two exchanges:
i) We give cash ($240k) and in exchange we charge 20.7% equity
ii) We deliver an awesome programme, packed with practical workshops, one-on-one coaching time and in-depth collaborative sessions with some of the world's leading brands. In exchange we charge for the programme.
Accelerators are not charities. That's not to say they are profit-hungry machines. We put an awful lot of man hours into developing and delivering the programme and we need to pay our team to do that!
I hope this helps explain why some accelerators both take equity and charge.
Good luck with your application.