What is the ruling on lying and feigning illness to obtain financial aid, and what is the ruling on someone who stole in their adolescence, repented, and wishes to know what to do without embarrassment?

It is forbidden to beg without need, and lying—which is informing contrary to reality—is also forbidden. The prohibition becomes more severe if it leads to unjustly taking others' money. Whoever does this is obligated to repent to Allah and return the money taken to its rightful owners.