It's investment into the ISAs themselves. Students will sign up for an ISA with Lambda School who will then package up a lot of ISAs and sell a percentage stake of them to investors. Lambda School gets some of their cash upfront and investors (in theory) get a revenue stream as students pay them back.

They've partnered with Edly, a marketplace to sell ISAs founded by Chris Ricciardi, the "grandfather of collateralized debt obligations".