It doesn't sound natural, no, but please tell us in your own words what you mean to say. What was wrong with the lesson? In what way was it not satisfying? Then we may be able to help you find the right expression.
"Get satisfied" would sound very odd here. The more idiomatic phrasing would be "I took a French conversation lesson with him, but I wasn't satisfied" or maybe "but I was dissatisfied." [Note the comma preceding the coordinating conjunction "but."]
The hypothetical context is that the student thought that the class was boring.
Could you tell me in what way "get satisfied" sound unnatural/odd in this sentence? Sexual, or just non-native speech? I have no idea.
Or is the combination of "couldn't" and "get satisfied" uncommon, or not idiomatic in this situation?
(Thank you bibliolept for your comment on the missing comma.)