Visitors to Rwanda can receive their entry visas upon arrival, without the need for prior application. The visas cost $50 only and are valid for 30 days.
As usual, a travel document (e.g., passport) valid for more than 6 months is required. There is no visa fee for visitors with passports from African countries and some other countries.

Please see carefully this: https://www.migration.gov.rw/visa/visitors-visa

(Also see: “V5- Conference and meetings” on the sidebar of that website)