Is it permissible for a wife to go out to attend lessons at the Zawiya without her husband's permission?

The general principle is that a woman should stay in her home and not leave except with her husband's permission, unless there is a legitimate religious justification. If the knowledge is something she is obligated to learn, such as knowledge that rectifies her creed, acts of worship, and transactions, and her husband does not suffice her by teaching it to her or providing a means for her to learn it, then it is permissible for her to go out to seek that knowledge without his permission. Otherwise, it is not. The spouses should be supportive of each other in seeking knowledge, and they can utilize the available means of acquiring knowledge via the internet.