KYC, which means Know Your Customer, is a defined regulatory process where users or entities are verified to know their authenticity and the source of their income. This is done to stem the fraud, and terrorism financing.
Documents are usually used to verify customers. The documents you would require of your customers would be a function of the countries in which you operate.
If you are a Nigerian lender operating on the Lendsqr platform, it is expected that you serve Nigerian borrowers, and their KYC would be verified with Nigerian-issued identity documents. If in doubt, consult the regulator for the country in which you operate.