We are going to launch/this three-crores project/within the next few months./No error.

The error is in the Part B. Units of counting -pair,dozen,gross,hundred,thousand,score when used after numbers retain their singular form.

Also,with exact number we use singular form.Eg-3 crore,2 lakh.

With indefinite plur5al no,we use plural form.

Eg-lakhs of people,crores of rupees.

Here they mentions,3 the exact amount ,which denotes that they are going to launch 3 crore project with in next few months.

If we use `crores' then it denotes the number of projects valuing 3 crores & above .