The later models will, especially Schwinns, had an old Raleigh I finally gave up on( gave it to Kid to convert to a gas powered motor bike.) Been working on a cheap steel framed step thru ebike, what stopped Me from going middrive was the BB was an odd width.Next bike will be ready made for sure.BTDT for decades, I've worked in the bicycle industry since late 80's; I've converted MTBs into ebikes since 2013.
With cheap & capable ebikes that are available on the market, there is not need to go through the trial & error of converting non-well-suited bicycles into ebikes.
No need to risk the injury of riding a bicycle that's not designed to handle the stress from extra power output & speed of an ebike.
Spending more money to convert a frame that's not designed to handle the stress; I hope no one thinks that's a safe/economical practice.
That cruiser frame likely does not have the rear hub spacing to accommodate a hub motor with a drive sprocket.