It is very time consuming to waterproof a basement. We let proffessionals do ours.
If it really floods, you've got a serious issue to take care of. There are various methods, like French drains and sump pumps, or diverting the water from outside. You should read up on this, then call in a reputable professional water-proofing firm. Check their licensing, and get a few estimates. Use the estimate interview to ask lots of questions. Unchecked hydrostatic pressure can damage your foundation.
This is something likely best left to pro’s unfortunately as they’ll be able to best understand and solve your issues the best way, most efficiently and cost efficiently.