Is it permissible to learn the English language through a paid course on the Telegram app, knowing that I cannot afford its cost due to my low salary, and does this fall under the category of usufruct that permits its use?

Intellectual property rights are legally recognized in Islamic law, and it is forbidden to infringe upon them as long as they are preserved for their owners. This is the fatwa of most Fiqh academies. If this course is paid, it is not permissible for you to take it without the permission of its owners, even if you cannot afford its price, because there are free alternatives for learning the language.