Health insurance in Africa, advice please

Hi all, I'm going to travel soon to Africa, can you help me please with health insurance if someone has experience? I'm traveling to Tanzania ( there I've heard insurance is mandatory on entrance), after that Malawi, Zambia, Botswana and Namibia.
– what insurance did you choose?
– was it good/do you recommend?
– how much did it cost?
– do you need to pay upfront and get money from insurance later or they pay directly?
– can you go to any hospital or is it only specific ones?
– anything else I need to know?
Thanks and have a nice day.