Is it permissible for me to take 50 Riyals in exchange for obtaining insurance for a colleague, and is it permissible for me to take a fee from the owner of a services office in exchange for bringing him clients?

Insurance can be permissible (cooperative, Takaful) or impermissible (commercial). If the insurance system adopted by the office is permissible, then it is permissible to attract clients for it and to take a commission for that, as a form of "Ju'alah" (a stipulated reward for a service). However, taking an additional amount when obtaining insurance for a colleague as an agent is not permissible without the knowledge of the principal.