@Das I have schizoaffective disorder. I also have the same problem. You are correct that this is a negative symptom of schizophrenia. It makes things harder, but I did manage to successfully complete my course in the end. I'll write out a list of things that helped me and I hope something works for you.
1. Check in with your treating doctor. It may be possible to change medication in a way that could help.
2. There are certain types of supplements that can help with focus. Always check with a pharmacist before taking anything though, as some things can interact with anti-psychotic medication. Ideally, your doctor can give you advice about what supplements to take, but you can also check in with an allied health professional such as a naturopath, Chinese herbalist or osteopath. Always keep your treating doctor in the loop about what you are trying. Beware of stimulant type drugs (including those found in "natural" over-the-counter tablets and powders) as they can cause a psychotic episode.
3. If you find you can't focus, have a stretch and get a glass of water. Keep doing this every time you can't focus. If you find you are losing focus more than once every ten minutes, then take a break.
4. Make sure you are getting enough sleep. A lack of sleep makes this so much worse for me.
5. Make sure you do some movement every time you have a study break. Walk, dance, and yoga were all very helpful in helping my brain to recharge. Reading and social media time during study breaks made my brain fuzzier.
6. Nibbing on some fresh veggies and fruit. Having something light in my stomach helped me. The crunch in raw veggies and fruit can also signal to your brain to wake up.
7. Sometimes putting on music and some scents in your study space can help. Lavendar and peppermint scents can help with focus and memory.
8. Set realistic goals. I found that I could only concentrate for 20 minutes at a time. So I would take a break every 20 minutes. I found I could actually get 3 hours of study done a day, all in 20-minute blocks.
9. Consider if part time studying would be better for you. Most courses have to provide a part time option for people if they have a medical condition/disability. I could only cope with part time.
10. Give yourself credit. The fact you are even attempting a course while dealing with schizophrenia is a huge achievement. You should be proud of yourself for giving this a go.