Yes some.packages having no flights included so you need to pay and even after credits redeemed you need to pay very less amount in some packages , all are not fully free you can try for Goa.
Yes, with most packages you have to pay a discounted fees. Also if you redeem in twin sharing then your partner also have to pay a discount rate to avail the offer. Sadly, non of the packages are fully paid, not even for solo.
While redeem your credits, you have to pay certain amount for package. Though they saying "Get Paid To Travel" but at the end you have to pay some amount
You will need to pay some amount, depends on the package you want to avail, your travel partner needs to pay some amount as well which according to tripoto is discounted rate