You will be introduced to mods and how to purchase and apply them early in the career.
Once you have selected a race, you can add and purchase new Mods from the "MODS" option in the pre-race menu.
There are five different Mod packs available to purchase in the Select Mods screen which range from 12,000 CR to 300,000 CR. The higher value packs offer a bigger % boost for each type of card. The best I have seen so far is a 60% cash boost from the 300,000 CR pack. It's random which Mods you get in each pack, so you will most likely need to open multiple packs in order to get the credit boost ones needed for this achievement.
noted in the comments that he/she received a Super Rare level Boost mod called Windfall that will do +100% Credit in the 300,000 CR pack.
You can select three Mods to use before each race, and the credit boost ones are single use items only. Once you have three or less credit boosts Mods that offer a 100% increase overall, you can add them by pressing
on each one and adding them to an empty slot. If you have a lot of cards, you can use the
button to filter them to show only credit boost ones.
Once you have the Mods selected, press
to go back to the pre-race options screen, and start the race. The achievement will unlock at the end when you are being shown your XP and credit rewards.