Ann: Quarterly Activities/Appendix 5B Cash Flow Report, page-89

"The government could have easily influenced a bank in such a corrupt country as Angola to fund already."

Maybe it's because there won't be any corruption. The quotas placed on banks to lend to the agricultural sector and the government loan guarantees for the sector should be more than enough to help Minbos secure the funding. That might take a bit more time than it might if corruption was involved but it is a much better outcome.
If corruption was needed, why would the government put in place the quotas and the loan guarantees?