Just adding my 2 cents worth.
I've just done 2 cross-connects at KUL. One was a 2 hour, and the other a overnighter.
The 2 hour cross connect, both flights landed/departed from the Satellite Terminal. I had my Boarding Pass printed for the second sector before arrival into KUL.
Lounge access didn't work. To take advantage of lounge access, you need a coupon/voucher from the Airline Agent. I found this out from the lounge attendant at the Sama Sama Airside Transit Hotel, which is one of the venues that Malindo use.
In the Satellite Terminal there was no Malindo agent in attendance at the airline counters to provide the voucher. I was told I had to catch the train to the Main Terminal to get the voucher. I didn't bother because with all the faffing around it was now only a hour before my second flight departed.
The overnight experience worked much better. The checkin agent provided the necessary coupon, which provided a whole range of options to spend 30/40 RM allowance. After seeing the Sama Sama Lounge option I avoided that (it looked very basic) and chose the Flightclub. The allowance covered a very decent breakfast and a cup of coffee.