I wrote the office of the Canadian Ambassador to Angola to ask for clarification on the "ban" on Islam. This is what their office replied:
We are not aware of any “ban” on Islam in Angola, however we are aware that many religious groups have difficulty registering in Angola.So no ban, but it doesn't mean Muslims are not operating with difficulty there.
The Cairo Post has a very enlightening article on the situation.
In sum, there has been no legislation to prohibit Islam in Angola.
However, Islam has not been registered as an official religion, as the law requires.
To register as an official religion, the body must have at least 100 000 members. Registration gives the religious body the right to build houses of worship.
Since the overwhelming majority of Muslims in Angola are illegal aliens, their numbers cannot be counted towards registration.
That means that whatever mosques are built to service this population of Muslims are illegal structures.
These mosques may service both legal and illegal residents of Angola.
The purpose of the clampdown is, of course, to fight Islamism. The fear is that foreign elements are gaining access to Angola to spread jihad.
Given the focus on fighting Islam, given that mosques are de facto illegal in Angola, it gives the air of being a ban.
It's not a ban on Islam per se. A Muslim can choose to pray five times a day. And Muslims can gather to pray.
They just can't build mosques and the government doesn't recognize them.
If the Muslim community could gather 100 000 legal residents to sign up and register, perhaps they could obtain registration.
Maybe. Because the government knows that if such a registration takes place, a lot of illegals will take advantage of those mosques.