I’m a regular runner and I agree with the posts above. Get some decent shoes – find a running shop that puts you on a treadmill etc, watches your style and judges whether you over / under pronate. You should not need orthotics unless you have physio and they tell you so. Good shoes will cost you £60 upwards from a sports shop, but when you find a pair that fit, you can replace them with a new pair online without needing to be re-fitted. running brands tend to stick to the same design every year, higher number in the name, different colours, same shoe.
Build up your mileage slowly. If you are fit from the bike, you can run many times further than your body can handle at this stage. Running is an impact sport, and your joints etc need to build up to this. 5k 10k now, 10m in a few months. On decent running shoes. Otherwise you can start bad habits leading to permananent problems.