How were the Christian crusaders able to get supplies while deep
behind Muslim controlled territory?

the imf provides economic advice and loans to developing countries.

economic advice:

policy advice to governments and central banks based on analysis of economic trends and cross-country experiences; research, statistics, forecasts, and analysis based on tracking of global, regional, and individual economies and markets; technical assistance and training to countries improve the management of their economies.

loans:

loans to countries overcome economic difficulties; concessional loans to fight poverty.

these are the goals the fund wants to achive.