To join specific programs at IVHQ you might need certain things (e.g. if you are going to do medical stuff, you're probably going to need training for that), but for the Nakavango program I went on, you don't need much more than you would for regular travel such as a passport, your flights and tell them your itinerary. They also required you get a business visa for Zimbabwe (check the gov website for requirements), vaccinations, a criminal record check, insurance, and your program fees. If you look more closely at other IVHQ programs, such as teaching gigs or ocean conservation they should tell you more about any sort of training or experience you need.
To join specific programs at IVHQ you might need certain things (e.g. if you are going to do medical stuff, you're probably going to need training for that), but for the Nakavango program I went on, you don't need much more than you would for regular travel such as a passport, your flights and tell them your itinerary. They also required you get a business visa for Zimbabwe (check the gov website for requirements), vaccinations, a criminal record check, insurance, and your program fees. If you look more closely at other IVHQ programs, such as teaching gigs or ocean conservation they should tell you more about any sort of training or experience you need.