Could you be a little bit more specific with your issue?
Is this only with SAI?
Is your tablet driver updated and compatible?
Have you tried re-installing/restarting your driver?
Is your tablet compatible with SAI?
Which tablet do you have?
Is it lagging and has no pen pressure??
Also, you could buy it tbh. Like, it's pretty dang cheap and well worth the money imo.
You could just google around for free versions too, or like cracked ones, y'know?
Otherwise idm putting my sai in a zip folder n sending it to you, just like fyi tho, i dont have the newest version with the transparency option, so if u want the transparency option u will probably have to ask someone else or download from elsewhere